June 2021 Review

Today we are taking a look back at a very eventful June 2021.

(if you are reading this in the distant future some of the dashboards below may have updated to reflect new data or formatting, or they may be broken, or they may no longer make sense. To see the original images for this post refer to this twitter thread.) 

As June ends we are still in the middle of a historic heatwave. Obviously we will be talking about that today, but we can't do a real heatwave recap yet because it isn't over. So this post will be about June, and then in a few days we will be back with a giant look at the great heatwave of 2021.

While we are waiting for the heatwave to end, if you are looking for some historic context we did a heatwave pre-cap last week:

But let's talk about June 2021.

High Temperatures
June 2021 started off warm with a few days at the top of our 30-year range. Then we had a cooler week with a few days just below average, and with June 8th as the coldest at 16°C. Then it was warm, then average, then warm, and then really, really, really warm.

Overall the month had 23 Highs above average and 7 below. That included new daily records of 34.2°C for June 28°C, and 37°C for June 30th, as well as 3 more warmest-in-30-years Highs.

Looking at the numbers we had 24 days with Highs that hit 20°C, compared to an average of about 18 for June. That included:
  • 15 days hit 25°C, when June averages about 5.
  • 6 days hit 30°C, compared to an average of about 0.5.
  • 2 days hit 35°C, with 36.2°C on June 29th and 37°C on June 30th. The last time that Blatchford had any day which hit 35°C was in 1937.

Warm Days So Far
So far the summer of 2021 has had 38 days hit 20°C, which is a little bit more than average for this point of the year. 2020 and 2019 both only had 29, while 2018 was way up at 52, and 2016 had 45.

For 25°C days we have had 15, compared to an average of around 10~12. 2020 was down at 4 and 2019 had 6, while 2018 was way up at 25, and 2015-2018 were all pretty high.

Hot Days Each Year
Here we have the number of 30°C days for the whole year, not just for January-June. So far we have had 6 days hit 30°C: one on June 22nd, and then 5 as part of the end-of-June heatwave. 

The average for an entire year is around 4. Several recent years like 2020, 2019, 2016, 2014, etc. were all low with 1 or 2. But 2018 had 7, 2018 had 6, 2015 had 9, and back in 2002 there were 13. And 1961 has the record with 14.

Super-Hot Days
Since 1880 we have only had 21 days hit 34°C, and 3 of those were in June 2021: June 28th at 34.2°C, June 29th at 36.2°C (our 4th warmest High ever recorded), and June 30th at 37°C.

June 30th came very close to Edmonton's warmest High ever recorded at 37.2°C on June 29th, 1937, but it didn't quite make it. June 29th, 1937 was also the last time that Blatchford had recorded a High of 35°C, for a gap of 84 years to the day. We will talk more about super-hot days in a few days during out heatwave recap.

Low Temperatures
For the Low temperatures June 2021 set 7 daily records. That includes the warmest overnight Low ever recorded, at 22.8°C on June 30th. That broke the previous record of 21.4°C set on July 14, 2007. Even with all of the records there were still 8 Lows below average though, with June 8th as the coldest at 6.9°C.

For the Lows we had 9 nights above 15°C, when June's average is 2. That included 2 nights above 20°C, and recently only June 2002 had another night that warm.

Warm Lows
This chart is normally used to talk about really cold Lows, so it's set up backwards for the summer. But today please pretend that blue means "warm" as we look at Lows of 17°C or more. 

For January-June 2021 we had 6 Lows hit 17°C, while no other January-June has had more than 2.

Really Warm Lows
And here is Edmonton's entire history of 20°C overnight Lows. There have been 11 in total, including 2 in 2021, 2 in 2007, and 2 in 1880. 

Edmonton's very first "modern" temperature reading is from July 11, 1880. Those 2 overnight Lows of 20°C on July 18 and July 22, 1880 are from the 8th and 12th days with records, ever. Because of that it seems like maybe they didn't have the routine down yet, and maybe instead of measuring the coldest temperature at around 7AM, maybe they took the reading a little later in the day. (it was a Sunday and a Thursday).

Warm and Cold Months
And so June 2021's average High of 24.947°C ranks as the #1 warmest June on record, just barely beating out June 1961 at 24.943°C. The average Low of 13°C is also the warmest June on record, easily beating 12.5°C from 1961 and 1970.

June 2020 and 2019 were both below average, but recently 2021, 2018, 2016 and 2015 were all top-15 Highs and top-10 Lows.

June 2021 was still a long way from our warmest month on record though, with July 2007's average High at 26.6°C, and August 1981's at 26.8°C.

June 2021 Across Canada
June 2021 was warm in cities all across Canada. The Highs ranged from 2.5°C warmer than the 20th century average for Vancouver, to 4.2°C for Edmonton, and 4.7°C for Calgary. The Lows weren't quite as warm, ranging from 1.3°C above the 20th century average for Regina to 4.4°C for Edmonton.

Here we have the whole history of June Highs for these cities. 2021 was a top-10 June for every city here with the exception of St. John's in 11th spot.

How Warm is 2021 So Far...?
This chart adds up all of the above and below temperatures for each day of the year. For warm days the line goes up, and for cold days it goes down. At the end of June 2021 the Highs are sitting in the 18th warmest spot, and for the Lows it is 26th warmest. So over all 2021 is about 1.2°C warmer than the 20th century average so far.

The June heatwave shows up with the red line ticking up near the end, but it's not enough to offset the dip from the the 2 week deepfreeze that we had in February. 2021 is still a warm year, but it's well below a really warm year like 2016 which was at 2.4°C warmer than the 20th century average by this point of the year, and ended at 2.9°C.

Looking at 2021 so far across Canada, Edmonton's #18 Highs are right in the middle of the pack. For Winnipeg and Montréal 2021 has been a #4 year so far, while in Calgary it's #26 and in Vancouver it's #28.

Monthly Precipitation
On average June gets 75mm of precipitation, and in 2021 Blatchford only had 24mm, the International had 31.7mm, and Stony Plain had 34.8mm. That's a bottom-10 June for Blatchford going back to 1880, and also bottom-10 for the International and Stony Plain going back to the 1960s.

2021 Precipitation So Far
By the end of June we average about 206mm of preciptation for the year. The International isn't too far off at 164mm, mostly thanks to a rainy May. Stony Plain is quite low at 126mm, and Blatchford is down at 109mm. For Blatchford that is another bottom-10 since 1880.

This chart is always a little messy, but it has the cumulative precipitation for 9 cities across Canada. Edmonton's 109mm is right at the bottom, although Calgary and Winnipeg are both down there with bottom-10 years as well. St. John's is at the top with 699mm, which is pretty average for St. John's.

July Temperatures
And what might we expect for July? July's average High is about 23.5°C, which is a little bit cooler than the record-breaking June which we just had. On average July has about 25 days which hit 20°C, including about 10 at 25°C. Most July's will get at least one 30°C day, but recently 2020, 2019 and 2016 didn't. The Lows are usually very boring, with almost all of them falling between 10-15°C, and the rest either a little warmer or a little cooler. July is also usually our rainest month, with an average of 90mm.

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