Canadian Monthly Temperature Anomalies 2010

CBC pronounced 2010 Canada’s warmest year on record.  I pretty much live outside all the time and have a pretty good sense of the weather.  For me 2010 will be remembered as the year without a summer.  So I thought I would dig deeper than a single average covering such a large landmass.

I data mined the monthly means for a representative cross section of Canada.  In the chart, I have color-coded the monthly anomalies as calculated by the delta between the monthly mean and the monthly averages from Environment Canada from their 1971-2000 dataset.  The results show what is hidden in an average.

Also included is a scaled 2010 monthly sea surface temperature graph to highlight its effect on Western Canada.

2010 Monthly Temps in 8 Canadian Regions

You may need to blow this up as there is plenty of information here (click it to enlarge.)

I note the following observations.

1. Canadian weather is regional.  It is a product of regional dynamics.

2.  Warm anomalies occurred in the coldest months.

3.  Cold anomalies occurred in the warmest months and coincide with the switch between warm Pacific water and cold Pacific water as shown in the graph.

4.  Based on 1&2, temperature extremes were decreased.  2010 Canadian weather data was primarily presented as being extreme yet temperature range was actually decreased.

5.  There appears to be a lag of a couple months between the peak el Niño in January and the March anomalies.  There also appears to be a “pulse” of La Niña making its way from west to east.

6.  As Western Canada chills in summer, a pool of warm water in the N. Atlantic warmed eastern Canada.  Here is July 2010 sea surface temps showing the warm pool of water off eastern Canada.


A yearly national temperature average conveys no practical information.  The claim of hottest year ever bears little resemblence to the data above even if it may be mathematically correct (UHI effects and other data corruption notwithstanding.)


Method and Sources

I chose weather stations that represented a cross section of Canadian cities in all the regions.  Since 99% of Canada’s population lives near these stations, they seemed most relevant though clearly they represent populated Canada not geographic Canada.  I first went to Environment Canada’s archive but found it to be swiss cheesed with missing data for many of my stations (hence the inclusion of little known Geraldton ON which is my proxy for Thunder Bay.)  Above is Environment Canada’s less than usefull database.

To solve this problem, I used the database from weatherunderground which downloads and archives the daily weather data from these same stations that Environment Canada uses, primarily airports.  They can be cross checked by their station ID number to ensure that means are compared to the correct data set.


Environment Canada’s 1971-2000 Canadian Database temp averages

Weatherunderground data

El Niño/La Niña data

Unisys SST archive

Map showing locations of station data.

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8 Responses to Canadian Monthly Temperature Anomalies 2010

  1. d_abes says:

    Hey dave, any data available from far-north stations? One from N60degrees would help IMO.

    • daviditron says:

      Hey d_abes,
      I purposefully cherry picked the populated southern stations since that’s where we all live and work. The 2010 average is higher than other years due to warm water anomalies in the far north. It struck me as irrelevant whether Baffin Island was tilting the average since this is a short term anomaly that affects almost no one. It creates a misleading headline. “Canada” was not warm in 2010, just parts of it were less cold for part of the time. Iqaluit’s Feb 2010 average is -17 which is 11 degrees warmer than its longer term average of -28. Minus 17 is hardly deserves the term “hot” and certainly not “hottest!”

      As far as station data goes, the link to Environment Canada gives you a station list in Yukon, NWT and Nunavut with average monthly means. You can then plug these stations into Weatherunderground to get 2010 monthly means and calculate the anomalies yourself.

  2. Elizabeth says:

    Thanks for the post.

    Our weather in Grande Prairie varies immensely from Calgary and even Edmonton. In fact, where I actually live (28 kilometres south of Grande Prairie) we often have dramatically different weather than across the wapiti river in Grande Prairie. Temperatures can vary up to 10 degrees from the airport to our home in winter. To be sure, it is usually a few degrees warmer at our home than on the highway, 1 kilometre away. Often, Grande Prairie has snow or fog when it is clear.

    Our family, having had a lot of experience travelling to different points between Grande Prairie and Grande Cache, particularly west, shows extreme variations, on the same day, sometimes with only 10 kilometres between sites. This has confirmed our suspicions about the accuracy of temperature measuring stations and how this data is extrapolated to fill in the missing areas.

    • daviditron says:

      Hi Elizabeth,
      Yes, just as I tried to show that a yearly national average is meaningless, you correctly point out that even over a small distance, a daily temperature average can be a meaningless number!

  3. Philip sceviour says:

    I recently downloaded the raw historical data from RedDeer and Calgary Intl airport by month from environ. Canada and plotted the results. The trend for Red Deer airport, which is in the country, is more or less flat over the last 100 years. The data for Calgary shows a decided up trend for minimum monthly temps. Starting in the 1970s but no change in max. Monthly temps — hence the average is rising slightly. Of course anyone with local knowledge knows Calgary airport is now in the city, massively expanded and suffering UHI effects. My conclusion is that using data from a source such Calgary Intl airport overstates the case for AGW compared to using rural sites such as Red Deer.

    • daviditron says:

      Hey Philip, I’ve noticed the trend for less cold rather than hot in most stations that show increasing averages. I did a post from a while ago that contains some pictures of calgary at the start and end of the temperature rise from 1970-2000.
      It’s true that this is also a period of positive PDO and other things, but the UHI is pretty apparent.

    • Glacier says:

      Almost all weather stations in the world show the same trend; the lows are responsible for all the warming. As a matter of fact, as the world has warmed up, we have experienced less heat extremes even though the average has gone up over time. This is to be expected because the warmer planet has more GHG in the atmosphere, namely water vapour.

      Consider the extreme case with no GHG – the moon. On that inhospitable climate you get extreme heat and cold ever day. Now, if one were to slowly add an atmosphere to the moon similar to that of earth, the extremes would decrease over time even though the “average” would increase.

      David, I use EC’s data here for research:

      Here is an example graph for you:

  4. Pingback: Deconstructing UN press release | daviditron

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