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.