Record Watch: Cold July 17th

Between Saturday and Sunday it felt a bit like someone turned the summer off, and today was downright fall-like.

By 6pm we hit 16.9°C which isn't too bad, but earlier in the afternoon we were around 13°C and 14°C. How does that compare to the records?

July 17 Temperature History
The lowest high ever recorded for July 17 was 15.6°C, back in 1940.

16.9°C would put 2017 in the bottom-10. Recently, other years with a cold July 17 were 2000, 1986, 1980, and before that we have to go back to the 1940s and 1930s.

Cold High Temperatures for July 14 through 20th

If we look at the coldest High temperatures for this week of July, 2017 isn't in the top-50. July 14 1913 only reached 9.3°C, and July 15 1999 hit 11.1°C, but all of the other coldest days were around 13°C or 14°C.


Environment Canada's official high for July 17 2017 ended up being 18°C, even though the highest hourly temperature was 16.9°C at 5pm. So the afternoon was still really chilly, but the day overall wasn't even close to any records.


Edmonton's Heatwaves

Last winter we looked at Edmonton's historic deepfreezes, including the epic, 26 days below -21°C that occurred in January of 1969.

Today we're going to switch to the more topical subject of summer heatwaves:

30°C Heatwaves

Edmonton's longest-ever recorded 30°C heatwave was 6 consecutive days, from June 2-7 in 1961, and the second-longest was 5 consecutive days in July of 1941. They're shown in this chart in red and purple respectively, with the background showing the more typical temperature distribution that we've seen for 1996-2017.

Since 1880 there have also been 10 other 4-day, 30°C heatwaves. That's too many to show on this chart, so instead only the two most recent ones - from August 2008 and July 2002 - are included. And even more recently, both July 2012 and August 2015 had 3-day streaks.

Edmonton has never recorded a solid week of days above 30°C though, so maybe that's too high a bar? Lets try 28°C instead:

28°C Heatwaves

Using 28°C as a cutoff instead, we have had two weeklong heatwaves: 7 consecutive days in July 1920, and 10 consecutive days in July & August 1984. There were also 7 other 6-day heatwaves, in 1906, 1917, 1933, 1936, 1941, 1961 (both of which we saw in the last chart) and 1981.

2015 is included in this chart because it had 3 separate 5-day streaks, in June, July and August.

Now we'll lower the bar one more time to 25°C:

25°C Heatwaves

Edmonton's longest-recorded stretch of days above 25°C was 16 days in 1984, and that was an extension of the 28°C heatwave that we saw in the last chart. The runners-up are 1915 and 1981 both with 15-days above 25°C in August.

And at just under two weeks, Edmonton has had 4 other 13-day streaks, in 1895, 1917, 1922, and then most recently in July 2007 which appears on the chart.

Warm Days Each Year

Looking at consecutive warm days is a bit arbitrary, because there could be a string of hot days which is broken up by one still-fairly-warm 24.5°C. It's fun for trivia, but in this chart we've switched over to comparing the total number of very warm days that each year had.

This chart shows the total number of days at-or-above 25°C, 28°C and 30°C, and as it cycles through them the 5-year averages appear as dotted, blue lines.

For 30°C days we average around 5 each year, although recently that has ranged from 0 in 2005, to 9 in 2015, to 13 in 2002. And 1961 is the all-time winner, recording 14 days (6 of which we saw in the first chart today).

For 28°C days the average is about 10 each year, although again there's quite a bit of variability. 2015 had 21, while 2010 only had 2. 1961 is again the winner, with 28, while 1916 was the only year to record 0. (there were also two other years prior to 1900, but they're both missing quite a bit of data)

Finally, we average about 30 or 35 days at-or-above 25°C, from a warm year like 2015 with 52, to a cooler one like 2005 with 19. The all-time highest and lowest were 1898 with 64 and 1954 with only 10. The average has stayed pretty consistent over that last century though (as we've seen before, Edmonton isn't exactly getting hotter...it's more like we're getting less-cold)

2017 So Far

Here is where 2017 sits so far, compared to some of Edmonton's other, long 25°C heatwaves.

We are just at the end of a 6-day streak, and things are supposed to cool off for a few days, before warming up again later in the week. So far this year we've had 22 days at 25°C or above, 7 at 28°C or above, and 3 at 30°C or above (May 31, July 7 and July 9, all at 30.2°C). And we still have August and most of July left to go.

When we're in the middle of an Edmonton heatwave, it's always good to keep in mind that it will probably be brief.


June Review / July Preview

It's time for the monthly look back at recent temperatures.

High Temperatures

It might be tough to remember, but this May was really warm, with most of the month well above average. That carried over into the first week of June, before temperatures settled in closer to average for most of the month.

In May we had one all-time record, and six other recent-records. In June we only had two recent-records, on the 7th and 8th at 27.9°C and 27.5°C respectively.

Taking a closer look at the temperatures, with an average High of 22°C this was a pretty warm June, although not quite as warm as 2015 or 2016 which were both well above average.

This June we had 7 days above 25°C, which matches what we had in May. We didn't actually break 30°C, although we got close on June 26 at 29.9°C, while in May we did actually hit 30.2°C on the 30th. I only point that out because the warmest day last year was in May, and we'll have to see if that happens again this year.

Low Temperatures

For Low temperatures we broke an all-time record on June 8th, with the Low staying up at 17°C. Beyond that things started very warm, but were mostly a bit below average later in the month.

With an average of 11°C the Low temperatures this June were on the warmer side of things, and about the same as 2015 and 2016.


Did June seem rainy? We had some precipitation on about half of the days last month, but that's right around the average for this time of year. Late-June and all of July are Edmonton's monsoon season, after all.

But even though we had quite a few rainy days, the 58mm of total precipitation was below the average of 72mm, below the 88mm that we had last June, and also below what we got in both April and May this year.

July Temperatures

And as we head into July the temperatures really flatten out.

Since 1998 the lowest-high temperature was 9°C on July 31, 2002, and there have only been 13 other days that didn't break 15°C. More typically about 25 days in July will break 20°C.

For Low temperatures, most nights should stay between 10-15°C, with a few above 15°C. Nights that are above 20°C are pretty rare, with only 2006 and 2007 recording any recently.