Monday, 2 September 2013

A Seasonal But Dry & Quiet Summer

     Although temperatures averaged right around normal this summer (June-July-August), temperature trends were not. The hot summer weather was confined to the beginning and ending of the summer season. From mid July to mid August, a period when we are normally at our hottest, we were instead very chilly with highs barely over 20°C and overnight lows frequently in the single digits. In total, there were 14 days at or above 30.0°C this summer, which is actually bang on the normal for an entire year.

     Although we managed to get much more rain than in the last 2 summers, we were still much drier than normal. This just goes to show how dry the summers of 2011 and 2012 really were. The reason for the dryness once again was the lack of thunderstorm activity. In total, there were 13 thunderstorm days this summer, tying for 5th least since 1953. Normal is 19 thunderstorm days.

Least thunderstorm days in a summer (Jun-Jul-Aug) since 1953

T-storm days in summer (J-J-A)
1961 & 2011
1956, 1967, 2008 & 2013

     In addition, Winnipeg's first thunderstorm of the year was on June 10. This was the second latest start to the thunderstorm season on record since 1953. We had also gone 289 consecutive days without a thunderstorm, the longest such period on record. So far this year, we have only had 13 thunderstorm days which would tie for 2nd least ever for an entire year since 1953 if we don't get a storm for the rest of the year. Will be interesting to see what happens..

     Not surprisingly, Winnipeg has seen the least amount of thunderstorm days so far this year as compared to all major cities outside BC and the Maritimes. The following map shows all the thunderstorm days some cities across the country have seen so far this year, up to and including August 31:

     What is interesting to note is how some northern communities have seen more storms than Winnipeg, including Timmins, Ontario (9 more than Wpg), Prince George, BC (3 more than Wpg) and even Thompson (6 more than Wpg)! (By the way, notes on how I gathered all this data can be found at the bottom of this post)

     The following is a list of additional interesting statistics of this summer (Jun-Jul-Aug):

Max humidex in Winnipeg: 40.4 on August 24
Max temperature in Winnipeg: 34.1°C on August 28
Minimum temperature in Winnipeg: 0.6°C on June 2
Daily records broken in Winnipeg: 3 (record low 5.6°C July 27 & 2 record high minimums of 21.4°C on Aug 24 and 19.7°C on Aug 25)
Severe thunderstorm days across Manitoba: 38
Confirmed tornadoes across Manitoba: 4

Ninette, Manitoba on July 13
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How thunderstorm days data was calculated:
By using archived METAR; this is to ensure that no thunderstorms are missed in between hourly observations. I use A Weather Moment's Metar viewer for this and I have to gather data every 4 days (takes about 15-20 minutes to gather the data for 43 cities because of some shortcuts I use)


  1. What a beautiful day it is, wish it was it was always like this.

    1. Couldn't agree more. Perfect September day.

  2. Holy cow, The GFS has 35 for friday! I shure hope we get that.

    1. If they are right, I bet we will break a record.

    2. A day or two of 30°C temperatures definitely looks possible late week/weekend. Summer's not over yet thankfully.

    3. Totally tanned manSeptember 03, 2013 10:36 am

      yippee!!! i love sumer. I can tan more! i love this.

  3. JJ,
    I noticed the forecast is 21 tomorrow and 33 thursday, is there a warm front or some other scientific thing happening? Thank you.

    1. I see it more as high pressure, which is currently in Saskatchewan moves off to our southeast, allowing for the return of a southerly/southwesterly flow over southern Manitoba tapping into the warmer temperatures to our west.
      However, I personally think 33°C is a little overdone for Thursday. I'm thinking more 29 to 30°C right now.

  4. EC's 33°C for tomorrow now dropped to a more reasonable 30°C.