The Great Heatwave(s) of July 2024

We're getting a bit of a reprieve from extreme heat, so let's take a look back at July's recent heatwaves. 

There was a short, extremely hot one from the 7th-11th, and then a long, still really hot one from the 15th-23rd:  

So many things happened, so we'll start with some summaries:

Highs In-a-Row

• 2 days of 34°C (3rd longest)
• 3 days of 33°C (2nd longest)
• 2 x 3 day streaks of 32°C (2nd longest)
• 7 days of 31°C & 30°C (tying 2021's record)
• 8 days of 29°C (tying 2021's record)
• 9 days of 28°C (2nd longest)

Highs

• The 4th and 8th hottest Highs ever recorded
• 7 daily records
• 2 35°C Highs (2nd most)
• 4 34°C Highs (tied for 1st)
• 7 33°C Highs (record)
• 8 32°C Highs (2nd most)
• 10 31°C Highs (2nd most)

Lows

• 3rd, 7th, 8th, 9th & 12th hottest Lows ever recorded
• 8 daily records
• 2 21°C Lows (tying the record) including 2 in-a-row (tying 2021)
• 6 20°C Lows (new record) including 3 in-a-row (tying 2021)
• 9 19°C Lows (new record) including 4 in-a-row (2nd longest)
• 12 18°C Lows (tying 2021) including 9 in-a-row (new record)

73.9°C

Before we get to the heat, think back to January which had a historically cold deepfreeze. It wasn't super-long like 2019, but it was extremely cold. It did some things that we hadn't seen since the 1960s or 1950s: 

https://edmontonweathernerdery.blogspot.com/2024/02/january-2024-review.html

With a deepfreeze & heatwave, Edmonton's 2024 temperatures spanned 73.9°C, from January 14th's Low of -37.7°C to July 10th's High of 36.2°C. That's the largest since 1950. 2021's heatwave & deepfreeze covered 72°C. 1886 & 1936 both have the record with 80.5°C.



Top 10

July 2024 had 2 of the top-10 hottest Highs ever recorded in Edmonton.

• July 10th's 36.2°C tied 2021 for #4.
• July 18th's 35.3°C ranked as #8

2021 & 2024 combined have 5 of the spots in the top 10.

July 2024 had 4 of the top-10 hottest Lows ever recorded in Edmonton. July 22nd's 21.6°C was #3, behind 2 nights from the 2021 heatdome, and then 7-9, and also 12.

2021 & 2024 combined have 6 spots in the top 10.



Hot Highs In-a-Row

So many streaks.

The most notable was probably 7 Highs in-a-row of both 30°C & 31°C, which tied 2021's record.

There were also: 

• 2 at 34°C (3rd longest)
• 3 at 33°C (2nd longest)
• 2 x 3 at 32°C (2nd longest) 
• 8 at 29°C (tying 2021's record) 
• 9 at 28°C (2nd longest)

Hot Highs

Summer isn't over, but so far 2024 has: 

• 2 35°C Highs (2nd most) 
•  4 34°C Highs (tied for 1st with 2021) 
•  7 33°C Highs (1st) 
•  8 32°C Highs (2nd most) 
•  10 31°C Highs (2nd most)

Hot Lows In-a-Row

And we had a lot of hot nights: 

• 2 21°C Lows in-a-row (tying 2021's record) 
• 6 20°C Lows (new record) with 3 in-a-row (tying 2021) 
• 9 19°C Lows (new record) with 4 in-a-row (2nd longest) 
• 12 18°C Lows (new record) with 9 in-a-row (new record)

Records

2024 set 7 records for daily Highs in July, and had 2 more earlier in the year.

With 9 records so far that ties 1910 for the year with the 3rd most record Highs. 

The only years with more were 1934 with 10, and 1889 with 14 (it had a very warm spring).

2024 set 8 records for daily Lows in July, and had 2 more earlier in the year. 

So 10 record Lows in 2024, 15 in 2023, 10 in 2022 & 12 in 2021. That's 47 records in the past 4 years, or 13% of the year. Just for May-September 28% of the days have had record Lows.



Calgary

While Edmonton was well into the 30s, Calgary spent a bunch of July near 30°C.

Their heatwave wasn't as extreme, but it did have some notable events: 

• 4 32°C Highs in-a-row (2nd most) 
• 8 30°C Highs in-a-row (tying 1917's record) 
• 10 28°C Highs in-a-row (2nd most)

Calgary also had its hottest Low ever recorded on July 24th, 2024. 19.1°C broke 2021's record of 18.8°C. 

They also had 9 Lows in-a-row of 15°C, breaking 2021's record of 8.

Smoke

For posterity, it's worth remembering that forest fire smoke started to roll into Edmonton on July 19th. The heatwave continued until the 23rd, but the smoke likely supressed temperatures a bit.

And Calgary's all-time record Low on July 24th was an extremely smoky day.

June 2024 Review

It's time for our big look back at Edmonton weather for June 2024.

June 2024 was not a hot one. 

The average High of 20.2°C was the 97th warmest, and the average Low of 9.4°C was 51st warmest. That's similar to June 2019 & 2014.



High Temperatures

June had 12 Highs above our 30-year average, and 18 below. None of the Highs got close to the top of our 30-year range, but June 8th's High of 12.1°C was its coldest since 1957.

June averages:

• 18 Highs of 20°C, and 2024 had 16
• 5 Highs of 25°C, and 2024 had 4

The only Junes in recent years which reached 30°C were 2023 & 2021, and before that was 2015, 2008, 2006...


Low Temperatures

June 2024 had 11 Lows which were above our 30-year average, and 19 which were below. And 4 of those were the coldest in 30+ years. The coldest was 3.2°C on June 8th, so we were still well clear of frosts.

June's Lows usually don't vary much, and on average 27 days fall between 5-15°C. 2024 had 4 cold nights below 5°C, when the average is only 1.



Frost-Free Days

Blatchford & Stony Plain stayed above freezing in June, but the airport and Campsie both got a late frost on June 19th. That's about 3 weeks later than average for them. 

For the airport that was the latest frost since 2009, and for Campsie since 2002.



Warm & Cold Months

A cool June follows a cooler May. June's average High of 20.2°C was -0.6°C cooler than the 20th century average. The average Low of 9.4°C was 0.8°C warmer than average, and is a medium orange bubble.

Across the country June's highs were cool in the west, and warm everywhere else. That ranged from Dawson City at 3.2°C warmer than their 20th century average, down to Saskatoon at -2.1°C below theirs.



The Horserace

Halfway through the year, and 2024 is a little bit warmer than the 20th century average.

The Highs are 0.2°C warmer, and the Lows are 0.9°C warmer. Overall that is 0.6°C warmer, which would make this our 43rd warmest year.

Across the country the first six months of 2024 haven't been hot in the west.

But for Winnipeg through Halifax it's been a top-10 year so far. And for Ottawa, Montréal & Quebec City it's #1 or #2 (and Montréal just had a new #1 year in 2023).



Precipitation

June is usually our 2nd rainiest month, averaging 80mm of precipitation.

In 2024 Blatchford was at little low at 67mm, while the airport was down at 54mm.

June averages 14 days with rain, and Blatchford had 15 and the airport had 13.

By the end of June we average 206mm of precipitation. In 2024 Blatchford is just below that with 191mm, which the airport is down at 183mm.

For total precipitation for the year so far Halifax & St. John's are up over 800mm, while Dawson City & Kelowna are below 150mm. Calgary's 297mm is well ahead of Edmonton's 191mm.

For big June storms:

• Quebec City had 56mm on the 23rd
• Montréal had 52mm on the 23rd
• Toronto had 51mm on the 20th
• St. John's had 47mm on the 25th

Edmonton's biggest was 30.7mm on the 3rd.


July

For July, the average High is about 23.5°C. It has around 25 days reach 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.

July is also usually our rainiest month, with an average of 90mm.