Canada’s Only True Desert

The media, governments, and tourism marketers have long been promoting the South Okanagan region around Osoyoos, BC, as Canada’s only true desert — even though Osoyoos is only semi-arid (or semi-desert if you prefer). As we shall see below, it is not a “true desert” by any known scientific definition.


Osoyoos, British Columbia

Others have tried this type of scam before, but few with the success of Osoyoos.

One tourist website I stumbled across a number of years ago started out by admitting that Lillooet (another semi-arid town) receives about 330 mm (13 inches) of precipitation per year at the official weather station, but then went on to claim that other areas of the valley where no weather stations have ever existed actually received less than 50 mm (2 inches). Don’t ask me how they would know that when no one was measuring it. Anyway, this would surely put the town in desert territory since  North America’s driest location — Death Valley, California — receives more than that. It seems that cooler heads have prevailed because this “information” has been scrubbed from the internet.

Inaccurate statistics placed on the internet become stubborn obstacles to truth long after they’ve been thoroughly debunked. One example being Della Falls on Vancouver Island, which has long been known as Canada’s tallest waterfall. Even a government website listed it as such until recently when some waterfall enthusiasts measured the waterfall. This bogus statistic is slowing being scrubbed from the internet and from government sources, but the misinformation lingers in the minds of the public.

Back to “Canada’s only true desert” again. There are dozens of websites promoting the false narrative that Osoyoos is Canada’s only desert such as this, this, this, and this. Yes, you read that last story right – they actually claim there are tarantulas living there, which, of course, is complete horsefeathers! And yet this #FakeNews has spread all the way to German.

Equally false is the statement about the area being part of the Sonoran Desert. Not to be outdone, even the federal and provincial governments got into the act calling this area part of the Great Basin Desert.


Those claims that Osoyoos is Canada’s only true desert and the northern extent of the Sonoran Desert are surprisingly easy to falsify.  The Sonoran Desert doesn’t even make it half way up Nevada, so that’s easy to debunk, but desert does exist into Washington State, and as we will see shortly, into British Columbia as well – just not Osoyoos.

The accepted definition of a desert is an area where the aridity index is less than 0.2 (think of it as evaporation being five times higher than precipitation); this index is calculated by taking the precipitation and dividing it by the potential evapotranspiration (similar to evaporation).

Desert (arid) is one of four dry climate classifications, accounting for 47% of the planet’s landmass.


Several different methods and formulas exist for determining the aridity. The best one is the Penman-Monteith method because it takes into account variables such as wind, humidity, sunshine, and air pressure.

Let’s look at the formula for a second.


Ahhh. Okay, let’s move on.

Less sophisticated methods are more often used to estimate potential evapotranspiration because the only variables available for most places are temperature and precipitation.

One of the more popular methods for determining aridity is the one employed by the Köppen climate classification. I will spare you the formula, but it yields similar results, placing Osoyoos in the wetter half of the semi-arid category. The Penman-Monteith method yields a more arid result, but at just over 0.28, still lands solidly within the semi-arid zone.

You might be saying to yourself at this point that Osoyoos might not be a true desert, but it’s the most arid place in Canada. After all, aridity is a function of both temperature and precipitation, and Osoyoos is both hot and dry. Temperature is an important component of aridity which is why Tuscon, Arizona is much more arid than Barrow, Alaska despite the fact that it gets more precipitation.

Similarly, Osoyoos is more arid than the far north for the same reason, but Osoyoos is not the most arid place in British Columbia. This alone surprises people who have been brainwashed into believing that Osoyoos is the driest place in Canada. Places drier than Osoyoos in Canada include the prairies around Medicine Hat, Kamloops, Merritt, Spences Bridge, the Fraser Canyon north of Lillooet, and parts of the Chilcotin from Kleena Kleene to the Fraser river. Drier (less precipitation), but not necessarily more arid.

The driest place of all is Ashcroft, which averages just over 200 mm (8″) per year. By comparison, Osoyoos averages 323 mm (12.7″) per year. This is a substantial inequality that the marginal temperature difference cannot overcome.

Using either of the methods above places Ashcroft in the arid category. The graph below shows the aridity of various places in Canada using the Penman-Monteith method.


The Köppen climate classification also locates Ashcroft in the arid or desert category, and this  map on Wikipedia confirms that.

So it is true that true desert exists in Canada, but it’s located 230 km to the northwest of Osoyoos in the village of Ashcroft. That’s why aliens, when they choose to visit us, crash in the Ashcroft area, and as we all know, UFOs always crash in “true deserts.” The X-files has documented such an event recently near Ashcroft.

xfiles1 xfiles2 xfiles3

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78 Responses to Canada’s Only True Desert

  1. John says:

    How can you say that Ashcroft has an arid or desert climate and averages just over 200mm a year when there isn’t a climate station there to give us this information?

    • Hi John, Ashcroft has had several weather stations over the years, covering 70 years from 1924 to the present. The current automated weather station has been in operation since 2010 with precipitation data missing until 2014. Similarly, Osoyoos has had several weather stations over the years from 1954 to the present, for a total of 62 years. The only weather station in operation today is the automated station which has been in operation since 1990, though it didn’t start recording precipitation with any sort of accuracy until recently.

      That’s the downside of modern automated weather stations tasked with measuring precipitation — they are notoriously inaccurate and subject to frequent errors and missing data points. That’s why precipitation is derived from the abandoned manual stations while wind and humidity data are extracted from the automated station for both Osoyoos and Ashcroft.

      In 2010, an automated weather station was also installed at Ashcroft. This is interesting, not only because it is the first time since 1989 that weather data is available for that village, but also because it is the first time that wind speed and humidity have been measured. If you recall, these two variables are needed in order to accurately calculate aridity. In addition, we need daily minimum and maximum temperature, hours of sunshine, and precipitation.

      The problem with this new station – like so many automated weather stations today – is that it has a lot of missing precipitation data. The other hole in our data set is the hours of sunshine. I figure that since Ashcroft is between 25 and 30% drier than Kamloops, it would be a safe to add 5% to the Kamloops numbers as a means of estimating Ashcroft.

      Using the past two years of data along with this sunshine estimate, I arrived a number very similar to Kamloops as far as Potential Evapo-Transpiration (PET) level. While Ashcroft gets more sunshine, and more temperature extremes, the higher windspeeds at Kamloops balances out the evaporation rate difference.

      Using the data and assumptions above, the PET for Ashcroft is 974.5mm of evaporation/year, so aridity comes down to dividing the actual precipitation by this number.

      Since we have little precipitation data in Ashcroft since the 1980s, we can deduce a number from older data.

      Looking at EC database, we observe the following data sets:

      Ashcroft = 187.0 mm ( 31 years between 1924 and 1970)
      Ashcroft = 206.3mm (6 years between 1973 and 1980)
      Ashcroft North = 209.7 mm (5 years between 1980 and 1985)

      Of course, precipitation is a huge factor when determining aridity, so I spent time time trying various ways of accurately calculating this figure.

      Method #1: Obtaining a weighted average, we get 192.7 mm/year.
      Aridity Index = 0.1977; Status: arid, but barely

      Method #2: Compare the data from the 70s and 80s to Kamloops and scale to today’s levels: 204.8 mm
      Aridity Index = 0.21; Status: semi-arid

      Method #3: Use the data from the 1924-1970 (when BC was much drier than it is today): 187 mm
      Aridity Index = 0.19; Status: arid.

      Method #4: Using the Köppen climate classification method (google it to see how it works). According this data as shown on the Köppen climate classification map, Ashcroft is a true desert even using the figure arrived at in method #2 above.

      So it’s not 100% certain that Ashcroft is a true desert, but it is by far the driest place in BC, and thus the most arid and desert-like place in the province. The second most arid place in BC is Spences Bridge, which I left off the chart for simplicity sake.

    • Judan, that’s an interesting comment that I will address in a future article. The short answer is that it’s debatable as to which city is the warmest in Canada. It really depends on who you define your terms. Windsor, ON has the warmest summers in Canada and Victoria, BC has the warmest winters in Canada.

  2. John says:

    Thanks for the detailed reply. You’ve done a good job at trying to get the most out of the limited data available. I’m glad to hear that a new climate station has been installed there.

    What I’m really intersted to know is how does one view the old climate station data for Ashcroft?

  3. Pingback: The Sunshine Tax | Questioning The Data

  4. Roger says:

    Now I will have to stop telling people I have been to the northern most desert in the world, based on the aridity index, referring to Carcross Desert, Yukon. Off to Ashcroft to re-establish my credibility. Thanks for the info..

  5. Les Robertson says:

    you might check Empress Alberta its drier then Osoyoos just a bit more precip. then Ashcroft but more sun and wind a higher evaporation rate summer heat too

    • Empress is slightly less arid than Medicine Hat even though it’s slightly drier. The reason being that it’s colder. Temperature is a large factor with evaporation. So is wind, but so is relative humidity, and BC has significantly drier air than Alberta during the summer months. As for sunshine, Alberta is sunny in the winter, but BC is just as sunny during the summer months, and that’s when it has the largest impact on aridity.

      Note that Empress gets 311.6mm/year while Ashcroft gets just over 200mm. That’s a significant difference that can’t easily be overcome by other factors like wind.

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  7. Les Robertson says:

    I,m not sure where you get your info…. Empress is not as dry as Ashcroft but the difference is not as great as you say from what i have seen . Southern Alberta gets more sunshine in the summer then ANY place in BC….compare Kamloops and Medicine Hat. Thunderstorms give Med Hat a bit more rain but still has more sun. Mannyberries more sun then Medicine Hat , Aden and Masinasin get more heat then Medicine Hat… both are pretty small places like Spences Bridge. There is a culture in BC to brag about there weather….. about tourism ??? Compare average temps in summer June July August at Medicine Hat and Kelownia airports. Medicine Hat is warmer. Also drier air in BC then Alberta in summer is very questionable. Summer Chinooks are very dry. Southern Alberta has the highest evaporation rate in Canada all things being considered.

    • Medicine Hat and Empress are very dry, but even Empress gets 50% more precipitation than Ashcroft. Even though the evaporation rate might higher, that’s a gap it cannot close. I did use monthly data for wind, sunshine, temperature, and humidity to calculate the results, so I think the chart is relatively correct. Perhaps Empress or some such place is drier, perhaps like that of Osoyoos in terms of aridity, but still a far cry from Ashcroft.

      Medicine Hat is the 2nd sunniest city in Canada during the summer (only Yellowknife with over 1000 hours gets more sunshine hours). Medicine Hat gets 983 hours. This compares to 927 at Lethbridge, 868 at Calgary, 867 at Victoria, 854 at Vernon, 845 at Kamloops and Saskatoon, and 824 at Kelowna.

      At the other end of the scale, we have Stewart, BC, with 409 hours.

      Yes, Medicine Hat gets more sunshine than Kamloops and Ashcroft, but it’s not just sunshine that matters. Rather, it’s the temperature in the open (or in the sun). Ashcroft is significantly hotter during the summer months than Medicine Hat. During the daytime, it’s 3 degrees hotter on average.

      Medicine Hat might have 15% more sunshine hours than Ashcroft, but the air is much cooler and the relative humidity is also higher. We’re talking 35% in Medicine Hat during the day in July verses 30% at Ashcroft.

      Another factor is wind. Medcine hat has an average windspeed of 12km/h in July versus only 9km/h for Kamloops (Ashcroft is similar). That definitely favours Medicine Hat, but this along with the extra sunshine is not enough to make up the difference for being more cooler and more humid.

  8. Les Robertson says:

    Some questions and corrections Yes, Yellowknife does have more hours of Sunshine in summer you are correct on that . Medicine Hat has a greater amount of sunshine that is possible….. Yellowknife .being in the far north the summer days are longer .In summer Medicine Hat has a higher % of sunlight about 72% if I recall correctly….. over Yellowknife. The 3 degree difference you claim for Kamloops being warmer on the average is incorrect. I,m talking records from both airports June July August Kamloops 25.1, 28.9, 28.3, Medicine Hat 23.4, 27.5, 27.0 thats a average of less then 2 degrees. Also the extreme humidex for Medicine Hat is considerably less then Kamloops which indicates in extreme heat the humidity in Kamloops would be higher. I have read in different agricultural papers over the years The Palliser triangle has the highest evaporation in Canada, now that might take winter into consideration as well .I have travelled all these places being discussed in all seasons many times. I have seen -20 in Osooyos with wind blowing cold but not typical. Medicine Hat +18 in winter warm but not typical. We all know Osoyoos or even Kamloops has warmer climate then southern Alberta. What people don,t understand you can get a hot summer chinook wind bringing the temperature up 30c before the sun even comes up and then cool to 20 and go back up again . I might add on this humidex thing Winnipeg has more days with humidex over 30c then Kamloops that fact suprised me . There are a lot of wrong info out about weather based on opinions not fact . We do know Osoyoos is NOT a desert. Really there is no true deserts in Canada in the classic sense. There is a culture in BC to brag about and exaggerate the qualities of there climate which is rated #3 in Canada

    • Hi there. Just a few clarifications. When I was talking about the degree difference, I was thinking of Ashcroft, which is 1.3 degrees warmer than Kamloops in July and just over 1 degree Celcius for the other two summer months. You can calculate this by looking at the past 5 years of data. Over that time Ashcroft has averaged 31.7C in July against Kamloops’ 30.4C. Now, since the 30 year average is lower than that, you have to subtract 1.5C, which brings you to an average of 30.2C.

      As for the extreme humdex, it’s pretty much useless. I mean, the highest humidex ever recorded in Canada is supposedly Castlegar, BC, and guess what, no one in their right mind would say Castlegar is anywhere as humid as southern Ontario… or Manitoba for that matter.

      Extremes mean nothing. The extreme coldest temperatures ever recorded in Canada were in the Yukon even though the Yukon is the mildest territory in Canada. The hottest temperature ever recorded in Canada occurred in Saskatchwan even though BC has much hotter summers.

      All that matters is averages, and guess what, the average afternoon relative humidity in Kamloops in July is 33.5%. Medicine Hat averages 36.6% in July. Ashcroft is much drier than either of those. We’re talking somewhere around 25.6% (I have only run a single year of comparison, but you get the idea).

      The Palliser triangle might have the highest evaporation in Canada because of the wind, but I suspect that it’s much like the “osoyoos is Canada’s only desert” claim, in that it might be urban legend more than anything.

      But even if we grant that it’s true, Ashcroft is much more arid because it’s much drier in terms of precipitation (it’s also much windier than most of southern BC including the likes of Osoyoos).

      What constitutes a desert is somewhat subjective, but if there is a desert in Canada it’s in Ashcroft.

      I absolutely agree with you that the quality of climate in BC is exaggerated, especially in the Okanagan Valley. I find the winters utterly depressing with almost no sunshine for two months. I’d much rather have colder winters with more sunshine. I also find the summers too hot.

  9. Alex says:

    Hello, I just happened about your website and find it very interesting. Could you please let me know the top 5 cities in SE and SW Ontario with the least humidity. Looking at places to retire to. And the overall top 3 least humid in Ontario. Thanking you in advance.

    • Hi Alex, I take it that you are thinking of humidity in the summer that drives up the humidex values? Southeastern Ontario is the most humid place in Canada. That would be the area around Windsor. Because of those high humidex values, a heat advisory is not triggered until the humidex hits 42°C. The rest of southern Ontario will get a heat advisory at 40°C while the north will have a heat advisory in effect at 36°C.

      Anything close to the lakes in southern Ontario will have higher humidity, although the Toronto Island airport is cooled off significantly because it’s surrounded by water. I would say that somewhere more inland from the lakes like London would be your best bet.

      The driest air would be in the north west area of the province. The only weather station with data is Big Trout Lake.

      Number of days per year with a humidex >=40:

      WINDSOR A = 7.22 days
      TORONTO BUTTONVILLE A = 4.41 days
      HAMILTON A = 3 days
      LONDON INT’L AIRPORT = 2.53 days
      PETAWAWA A = 2.25 days
      PETERBOROUGH A = 2.02 days
      TRENTON A = 1.63 days
      TORONTO ISLAND A = 1.54 days
      THUNDER BAY A = 1.2 days
      KINGSTON A = 1 days
      SAULT STE MARIE A = 0.86 days
      WIARTON A = 0.83 days
      KENORA A = 0.6 days
      TIMMINS VICTOR POWER A = 0.6 days
      SIOUX LOOKOUT A = 0.56 days
      GORE BAY A = 0.52 days
      KAPUSKASING A = 0.5 days
      NORTH BAY A = 0.44 days
      SUDBURY A = 0.4 days
      GERALDTON A = 0.24 days
      BIG TROUT LAKE = 0 days

      Number of days per year with a humidex >=35:

      WINDSOR A = 29.9 days
      HAMILTON A = 21.73 days
      TORONTO BUTTONVILLE A = 19.8 days
      TORONTO LESTER B. PEARSON INT’L A = 18.41 days
      LONDON INT’L AIRPORT = 18.14 days
      PETERBOROUGH A = 14.21 days
      TRENTON A = 13.89 days
      TORONTO ISLAND A = 13.63 days
      PETAWAWA A = 13.28 days
      KINGSTON A = 8.84 days
      WIARTON A = 8.3 days
      SAULT STE MARIE A = 7.67 days
      THUNDER BAY A = 6.8 days
      GORE BAY A = 5.57 days
      KAPUSKASING A = 5.23 days
      KENORA A = 5.22 days
      SUDBURY A = 5.21 days
      TIMMINS VICTOR POWER A = 4.97 days
      SIOUX LOOKOUT A = 4.83 days
      NORTH BAY A = 4.26 days
      GERALDTON A = 2.75 days
      BIG TROUT LAKE = 0.82 days

      • Alex says:

        Thank you so much for your very detailed answer…really appreciate it. I guess there is not many drier places to escape to in Ontario unless of course we go up North and then we have the winters 🙂

  10. thedesertoracle says:

    Hello and thanks for this interesting account of semi-desert locations in Canada. The U.S. desert absorbs a substantial population of Canadians each winter (mostly from BC and Alberta), and we are happy to have them as they behave so much better than the Americans. And quite a few of us who live in the Mojave Desert tend to escape north when the worst of summer hits here.

    Should note for the record, however, that the Sonoran Desert (land of the saguaro) reaches halfway up in southern Arizona … Nevada has a spot of the Mojave Desert at its southern tip, but the majority of the state is the same dry/cold Great Basin Desert that covers Eastern Oregon.

  11. Chasity says:

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  12. Joe says:

    Thanks for this info. What’s the annual sunshine hours for those bc locations?

    • Sunshine hours have never been recorded in Ashcroft, but Kamloops to the east averages 2080 hours per year. Ashcroft is probably sunnier given that it’s quite a bit drier, so maybe close to 2200 hours, although, precipitation does not always correlate with sunshine hours.

      For example, Osoyoos averages 1945 hours of sunshine per year while Victoria, which gets about twice the annual precipitation as Osoyoos is tried with Cranbrook as the sunniest place in the province with 2200 hours of sunshine annually.

      • Joe says:

        Thanks very much. Is Ashecroft also sunnier and less snowier in winter than Okanagan and the rest of bcs summer sunshine locations? I’ve been reading how cloudy and dreary most of southern Bc is compared to Alberta sk and Mb. In fact southern Ontario gets more sun than any place in southern Bc.

      • Joe says:

        Which BC city or area has the highest winter sunshine since the Okanagan valley and other bc so called sunny spots are dark and dreary.

    • Joe, check out this map showing sunshine hours:,-126.8830914,1780469m/data=!3m1!1e3!4m2!6m1!1s1ctInTLEvrthqnacsdXwQpX5NrsM?hl=en

      The Chilcotin area of the BC is the sunniest part of the province in the winter (Anahim Lake, Tatlayoko Lake, Tatla Lake, etc.). That’s the area in white and red. After that it’s the Peace River area (Fort St. John, Dawson Creek, etc.), but then you have to deal with the bitter cold.

      Now, parts of the Chilcotin are quite cold in the winter like Anahim Lake, BUT some areas like Tatlayoko Lake and Nemiah/Chilko Lake are as mild as the Okanagan in the winter, but with lots of sunshine! That’s why (in my view), the Nemiah Valley has the nicest weather in all of Canada.

      • Joe says:

        Warmer than lake cowichan and Vancouver island or close enough?

        • Much colder than Lake Cowichan or Vancouver, etc, but mild by interior standards. It it’s far drier and sunnier than the coast in the winter, and very nice because the precipitation comes down largely as snow. It might be -5C in Tatlayoko Lake, and -30C in Tatla Lake some 30km away, and that’s a huge difference when spending time outside playing pond hockey. Meanwhile, on Vancouver Island, you’re stuck in +5 and heavy rain, so no skating for you outdoors.

      • Joe says:

        Im guessing that valley is also very sunny dry even in summer and hot.

      • Fairly mild summers because of the higher elevation. Quite cool at night (around 5C as a low in July with highs in the mid 20s). Yes, quite dry year-round.

      • Joe says:

        Im liking the sounds of it but from the sunshine map there isnt much cities with population around.

      • Joe says:

        Im liking the sounds of it but from the sunshine map there arent much cities
        Or population around.
        Maybe the lowest hills and valleys are warmer/milder

      • Joe says:

        Thanks still cant get over canadas great secret

  13. Catherine Novis says:

    How’ve ignorant are you and everyone who posted a reply, not to mention everyone and every ngo & governmental body you mention? Obviously your publication does not attract the attention of either intellectuals or scientists.
    Strictly speaking, that is geologically, Canada’s only true & scientifically recognised desert is the Arctic, part of the Arctic polar desert, which the world’s second largest desert (Antarctic is largest) at 5.4 million square miles. I was waiting for this incontestable fact to be mentioned in the above article; but alas, reporting truth is apparently less important than good storytelling. Shame on you all!

    • Joe says:

      Who gives two lemons about the Arctic or Antarctic. They are irrelevant. If you care so much that they are a desert you should go live there and shut up. No one cares about cold deserts. No one except you. Now go away.

      • Catherine Novis says:

        Pearls of wisdom, from the mouth of a true humanitarian and intellectual.
        Because really, what scientific research is conducted in the Antarctic and Arctic?
        And there’s no environmental devastation, or melting polar ice caps & species eradication, so who really does care?
        Thanks for demonstrating that real way to prove one’s worth and to win a debate is through insults, not facts.
        Viva Les Alternative Facts!
        Live long and prosper:-)

    • The arctic is not actually a desert. Yes, Eureka, Nunavut is the driest place in Canada with a mere 79mm of precipitation, but it’s so cold there that there’s hardly any evaporation, so when you divide the total precipitation by the total evaporation, you do not get a low enough number to classify it as desert.

  14. Catherine Novis says:

    Correction to my above post: area of the Arctic Desert should read 5.4 million square km, not miles. Apologies for autocorrect.

  15. Joe says:

    When someone comes on here with this air of pompousness and starts acting all holier than thow criticizing and nitpicking needlessly, offending the op and disrupting the peace of the post by useless information they get what they deserve. It’s all in the presentation lady and you failed miserably.
    Have some courtesy and tact next time it goes a long way not the bubble you seem to be living in.

    • Catherine Novis says:

      It’s not pompous or “holier than thou” if it’s true:
      The Largest Desert:
      The two largest deserts on Earth are in the polar areas. The Antarctic Polar Desert covers the continent of Antarctica and has a size of about 5.5 million square miles. The second-largest desert is the Arctic Polar Desert. It extends over parts of Alaska, Canada, Greenland, Iceland, Norway, Sweden, Finland, and Russia. It has a surface area of about 5.4 million square miles.

      • There’s desert and there’s desert. There are a lot of places in the world that claim to be deserts which aren’t really by any scientific definition out there. In the context of this article, desert = arid.

        Given the fact that Eureka, Nunavut gets a mere 79.1 mm per year (by far the driest spot in the Canadian Arctic), the temperature is very cold, even in summer, so there’s hardly any evaporation to speak of. I will look into the numbers later when I have time and report back.

        • CAGEN says:

          The system of Aridity Index (AI) to which you are referring is Koppen’s Climate Classification.
          It is largely outdated, but since it’s your chosen formula, we shall apply it.

          Unfortunately, as you supply neither the average mean annual temperature (T) of Ashcroft, nor Ashcroft’s R value, but only Ashcroft’s mean annual precipitation of 200mm, we are unable to work out Ashcroft’s Koppen AI. We only have your word that it is more arid than Eureka.
          Nor do you if Ashcroft’s precipitation occurs in the colder months, the warmer months, or is evenly distributed.
          However, for your application of the formula to yield a rating of Arid for Ashcroft, the annual average temperature would have to be below 6C, assuming precipitation occurs mainly in the warmer months. I have taken the liberty of using P/10 to represent annual precipitation in cm, since it actually measured in mm.
          P/10 x 2 = 200/10 x 2 = 40
          (40 – 28)/2 = 6
          So let’s give Ashcroft the benefit of the doubt, and say it’s mean annual temperature is 5C.

          However, your application of the formula for Eureka is skewed.
          Using the formula you mention, 2 x T + 28, we get this: 2 x -15.5 = -31 + 28 = -3
          I am pretty sure that -3 is less than twice 7.91 (P/10x 2), or 15.82.
          That would mean Eureka is, by your application of the formula, well and truly classified as ‘arid’.

          However, I am not sure from where you get twice 7.91 (P/10 x 2). That’s not in the formula.
          The formula on the wikipedia link you give is this:
          Arid regions are defined as those where annual rainfall accumulation (in centimetres) is less than R/2, where R = 2 x T + 28 if rainfall occurs mainly in the hot season.
          Applying this formula likewise to an assumed annual temperature of 5C for Ashcroft (less than 6C, as was stated above), we get this:
          2 x 5 = 10 + 28 = 38
          Therefore R = 38, and R/2 = 19.
          Annual rainfall in Ashcroft is definitely above 19cm (20cm, didn’t you say?), so would be not classed as ‘arid’ within Koppen’s Aridity Index. For Ashcroft to be classified as ‘arid’ using the formula applied properly, R would have to equal 37 or less. This would mean the average temperature would have to be 4.5C or lower. Perhaps it is. I am not debating whether Ashcroft is a desert or not. Simply that it is not Canada’s only desert.
          Applying the above formula to Eureka, and not the strange one you inserted, gives us: R = -3, and R/2 = -6.

          Of course, polar deserts don’t really have a ‘hot season’, do they? But the summers do average temperatures from 0-10C, so it is certainly warmer than the winter. In fact, they don’t really even have rainfall either, but do have precipitation.
          It is worth noting even the language in that this formula is set up intuitively for non-polar regions, and is inapplicable to polar conditions.

          As is obvious from the result, this formula cannot be applied to Eureka, because you cannot have annual rainfall that is a negative number.
          The Aridity Index cannot be applied to polar climates because water is in an unavailable, frozen state, with temperatures averaging below -10C.
          The result of applying this formula inappropriately to polar deserts requires negative precipitation, which is, of course, impossible.
          That does not mean Polar Deserts cannot be classified as arid: it simply means their aridity cannot be measured using the same criteria as temperate climates.
          “The Arctic and Antarctic contain polar deserts…Arid environments occur at the poles, along the equator, on mountains, plateaus, below sea level, along coasts, and within mid-continents. They may be hot or cold climate types.”


          In Koppen’s system, the world is divided into 5 climate zones, and in only one of these zones (B), does the AI apply. The other 4 climate zones are defined by temperature alone, including the Polar zone (E).
          One cannot pick and chose to apply formulas when they are neither applicable nor appropriate.

          “Köppen’s classification is based on a subdivision of terrestrial climates into five major types, which are represented by the capital letters A, B, C, D, and E. Each of these climate types except for B is defined by temperature criteria. Type B designates climates in which the controlling factor on vegetation is dryness (rather than coldness). Type E climates (the coldest) are conventionally divided into tundra (ET) and snow/ice climates (EF).”

          And here, you can see that Koppen’s ‘E’ zones are not even mentioned in the below table, because the formula does not apply:

          Table K1 Climatic regions classification

          Full humid Semihumid Semiarid Arid

          Af As/Aw
          Cf Cs/Cw BS BW
          Df Ds/Dw

 pg. 442

          This table also demonstrates that Polar regions are in a separate classification to temperate humid/arid classifications:

          Table C3
          Correspondence between climatic and vegetation types

          Climate Vegetation type name Vegetation

          Rainy tropical Malayan Evergreen rain forest

          Subhumid tropical Nicaraguan Deciduous or monsoon forest

                           Timoran                Savanna forest or woodland
                                Visayan               Tropic grassland

          Warm semiarid Tampicoan Thorn forest, thorn scrub

                               Tamaulipan         Desert savanna, wetter parts

          Warm arid Tamaulipan Desert savanna, drier parts

                           Sonoran                Subtropic desert
                           Tripolian              Short grass; desert grass

          Hyperarid Atacaman “Barren” desert

          Rainy subtropical Kyushun Warm temperate rain forest

                            Argentinean           Prairie

          Summer-dry subtropical Mediterranean Sclerophyll woodland and scrub

          Rainy marine Tasman Subantarctic forest

          Wet-winter temperate Oregonian Conifer forest

          Rainy temperate. Virginian Mixed deciduous and conifer forest

          Cool semiarid Patagonian Cold desert, wetter parts

          Cool arid Patagonian Cold desert, drier parts

          Subpolar Alaskan Taiga forest

          Polar Aleutian Tundra and polar barrens

          After Putnam et al. (1960).

 pg. 219

      • The Koppen classification is useless, I agree. So using the Penman-Monteith (eg., potential evapotranspiration (PET) at Eureka is about 20 mm/year. That’s not even close to being arid. By contrast, Ashcroft (with an average annual temperature of 9 to 10C BTW) has about 1,050 mm of PET per year. This leaves Ashcroft far, far more arid than Eureka.

  16. Les Robertson says:

    I do agree with Questioning Data The Koppen classification is useless. As are as science is concerned it has its place. Catherine Novis and her intellectual stupidity is entertaining. I,m not against education I have 2 daughters with Medicine. I,m a college drop out by choice and proud of it. There is balance….. statistics and real conditions. These climate people forget the direct heat of the sun. Wind chill is another joke…. can be below freezing wind chill but water won,t freeze more later

    • Joe says:

      Agreed. What’s interesting is that plants aren’t affected by wind chill like humans are. About water not freezing by wind-chill is interesting. So if it’s 1c and a wind-chill of -5 water won’t freeze even in a little bucket?

  17. Joe says:

    To me a place with snow on the ground in mid January and July isn’t a Desert.

    • Catherine Novis says:

      Polar deserts have almost no precipitation…they are deserts, after all. They don’t have snow really, but whipped up ice and permafrost.

  18. Joe says:

    To me a place with snow on the ground in mid January and July isn’t a Desert.

  19. CAGEN says:

    It was actually I who said the Kloppen system was useless, not Questioning the Data, who chose it as his system of reference.
    It doesn’t really matter to me what people chose to believe, when the weight of evidence actually shows what I stated from the start.
    FYI – the driest place on earth is in the Antarctic – a polar desert.

    • I regret using the Koppen system in that reply because it has led to confusion. I was pressed for time at that moment, so just did a quick calculation. If you look at my followup reply AS WELL AS the actual article above, you will notice that Koppen is not the system used to discredit the arctic as a desert.

      Also, if Antarctic is a desert, why is the snow accumulating over time!? Answer: Because it’s not a desert! If it were a desert, EVAPORATION would outpace PRECIPITATION by a factor of 5, and that’s certainly not the case.

      • Catherine Novis says:

        You old charmer!
        Just when I go to leave you draw me back in with your wit & banter..

        One of the most extreme deserts in the world, these snow-free valleys harbour life, despite the hostile environment.

        The McMurdo Dry Valleys are a row of snow-free valleys in Antarctica region. It is one of the world’s most extreme deserts.

        The Dry Valleys are ice-free, or dry, because any precipitation that falls as snow on the valley floor is blown away by strong, dry katabatic winds, through the process of sublimation. The result is the Dry Valleys being cold, and one of the world’s most extreme deserts.

        • Snow-free? Is that picture taken in summer or winter? Somehow I doubt it’s the middle of winter. Even still, it’s highly doubtful that it’s a true desert. ie. that evaporation is 5 times precipitation. I’m not saying it’s not because I don’t have weather data for that location, but I’m skeptical.

          • Catherine Novis says:

            I will take ownership for having opened conversation on this website in a somewhat inflammatory fashion. But I did really think soon afterwards that an intelligent exchange might ensue. However, despite having provided numerous academic articles and scientific publications, the only responses I have received from this website are unsubstantiated opinions and childish insults. I will let those remarks stand as both a reflection of, and testament to, those who wrote them. It would appear that those who read “Questioning the Data” are ironically people who don’t wish to question the data at all, but to mindlessly follow. Please, and I sincerely mean this: continue your lives in peace. If you treat me, a harmless stranger, this way, I can only imagine how you treat those who are close to you, who can truly get under your skin. My mistake (and perhaps Sir David Attenborough’s too, for his remarks on the Polar Deserts in his award-winning documentary).

  20. Joe says:

    Cagen it’s so cold in the polar deserts winter or summer it really is meaningless and hard to wrap our mind around the data. To us humans the Atacama Sonoran Namib and Sahara is liveable there even if sparsely but who on earth could survive in a frigid polar deserts wasteland of ice and snow. Can’t even imagine it. That’s why it’s irrelevant and meaningless to most humans even if there’s no precipitation yearly. To us it matters very little in our lives.
    Ashcroft or most any desert outside the poles has more significance and meaning for us living breathing people. That’s my take

  21. Catherine Novis says:

    It’s been fun, but I’m signing off. Have other things that require my time & attention,

  22. Joe says:

    Catherine Novis go whip up yourself another frosty to keep that brain of yours under permafrost

    • Catherine Novis says:

      Wow, your logical and academically well informed retort has convinced me of the errors of my ways. I had never realised how childish insults can demonstrate true brilliance and insight. Thank you for this valuable lesson.

      • Joe says:

        Let me make it up to you with a nice Cold icy Smoothie.

        • Catherine Novis says:

          having opened conversation on this website in a somewhat inflammatory fashion. But I did really think soon afterwards that an intelligent exchange might ensue. However, despite having provided numerous academic articles and scientific publications, the only responses I have received from this website are unsubstantiated opinions and childish insults. I will let those remarks stand as both a reflection of, and testament to, those who wrote them. It would appear that those who read “Questioning the Data” are ironically people who don’t wish to question the data at all, but to mindlessly follow. Please, and I sincerely mean this: continue your lives in peace. If you treat me, a harmless stranger, this way, I can only imagine how you treat those who are close to you, who can truly get under your skin. My mistake (and perhaps Sir David Attenborough’s too, for his remarks on the Polar Deserts in his award-winning documentary).

  23. Joe says:

    Ok Catherine Novis on a serious note it seems like you didn’t read the evidence presented by questioning the data and Cagen and others then last week you snubbed us by stating you have better use of your time. Then you get upset when you get poked at?

  24. Catherine Novis says:

    Wasn’t snubbing anybody, and not really sure why anyone would be offended by my leaving the comments section. I do have other things that demand my time & attention, like a job (Acute Medical Nurse) and a family (3 children, one with special needs). I’m betting you have better things you could be doing with your time, too! Really, this is a regional opinion piece. But that doesn’t change the fact that evaporation is not a factor in defining Polar Deserts.
    Also, if you had actually read what CAGEN wrote, you’d recognise it was all in support of Polar Deserts. I am CAGEN.

    • There might be desert in Antarctic, but I don’t have to data to confirm or deny that. This article only deals with the Canadian situation, which, when we crunch the numbers reveals that Ashcroft is the most arid place in Canada (it has the highest moisture deficit in the country).

  25. Happy New year 2019 says:

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  26. Lilly Fuller says:

    Cool (i didn’t read it 🙂

  27. Rayne FullerWhite says:


  28. Brigitta Bonn says:

    Where does the Carcross Desert/Yukon, Canada fit in with Osoyoos, Great Basin Desert , Mojave Desert and Sonoran Desert. Are the first 4 connected? Carcross is far away from the others.

    • The Sonoran Desert is in Mexico and extreme southern California-Arizona. Bordering that desert is the Mojave Desert which extends halfway up Nevada and California. Bordering that to the north is the Great Basin Desert which extends up to the Oregon border. There’s no connection between that and the semi-arid region in Washington and southern BC (Osoyoos an the like). There is an area in Washington State that is classified as arid that’s isolated from the deserts further south, but it does not extend up to Osoyoos (because Osoyoos is not a true arid desert).

      As for the Carcross Desert, that’s just a windswept sandy spot that someone named a desert. It’s not a desert in the technical sense, but it does garner tourists because someone arbitrarily named it the northernmost desert.

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