2018/09/01

August Review / September Preview

The last few weeks have been pretty chilly, but how was August's weather overall?

High Temperatures

The month started warm, and on August 9th we set an all-time record High at 34.5°C, and then August 10th set a recent (since 1996) record at 31.6°C.

But right after that things flipped, and on August 12th we set an all-time record for coldest High down at 11.6°C, and then August 24th was a recent coldest High at 11.7°C.

Looking at the red & blue shading, the first 2 weeks were above average, the last week was below, and in between things a little bit warm.


When we look at the numbers, with an average High of 22.9°C 2018 was just a little bit warmer than the average-average of 22.5°C. That made this the lowest average High since 2011 at 22.5°C.

This August we did have 2 days which hit 30°C, when about three-quarters of the time August won't have any. The 12 days at 25°C was a bit above the average of 10 days, and the 23 days at 20°C was right on the recent average.


Hot Days This Summer

For the summer so far that brings us to a total of 54 days which hit 25°C. That's the most since 1961 which had 60. And that means 2018 makes Edmonton's Top-5 years for 25°C days, along with 1922 at 57, 1894 at 59, 1961 at 60, and 1898 at 64.

Our 19 days at 28°C is above the average of 15, but isn't particularly notable. Recently 2015 had 21 of them.

7 days at 30°C is also above the average of 4, but it's nothing extreme. Last year had 6, 2015 had 9, 2008 had 8, 2007 had 8, 2006 had 9, and 2002 had 13.

With the end of August we've probably seen the end of really hot days, but last September did have a day which hit 30°C, and one or two days at 25°C are pretty typical.


Low Temperatures

For the Low temperatures we set a recent warmest-Low on August 10th at 15.7°C, and then a recent cold-Low on August 25th at 3°C.


2018's average Low of 10.9°C was actually a little bit colder than that average-average of 11.3°C.

We also had 2 nights below 5°C, and the last time that happened was in 2002.


The Race for Edmonton's Warmest Summer

A few weeks ago we looked at Edmonton's Warmest & Coldest Summers, and at the time 2018 had a fairly commanding lead over the current #1 1998. Since then though, the smoke moved in, and we had some chilly days, and the lead disappeared. Right now 2018 and 1998 are basically tied, and the forecast is for another cool week, so 1998 will likely keep it's top spot. But assuming this September is "average" then the summer of 2018 will still rank in the Top-10 - along with other recent summer like 2017, 2016, 2015, 2013 and 2012.


Warm & Cold Months

This chart shows how the overall temperature for each month compares to recent years, and to the 20th century average. In 2018 May was really warm, June was pretty warm, and July was about average for recent years, which is about 2°C above the 20th century average.

With August's really warm start and really cool end the overall temperature was 1°C, but that was about 1°C colder than recent years.



This chart is a different way of viewing the same information, with the size of each bubble showing how much warmer or colder each month was compared to the 20th century average.

With this chart it's easier to compare various years, and we can see that overall 2018 had been pretty quiet compared to a warm year like 2016.

Edmonton's temperatures are much more variable in the winter than they are in the summer, and that's why in this chart the biggest bubbles are all in January, February, November & December, while June, July & August are all relatively tiny.

And of course there has to be an animated version showing the records going back to 1880:



Precipitation

For precipitation this August the International was right at the average, with 49mm. That was a bit higher than Blatchford which had 42mm, and also more than last August which had 41mm.


For the year so far that brings precipitation at the International Airport to 305mm, which is on the low side of things and around the 25th percentile. And Blatchford is 50mm below that at 244mm. Last year at the end of August the International was at around 376mm.


September Temperatures

As we move into September we should still have a week or two of 20°C days. And since 2008 every September has had at least 2 25°C days, although prior to 2008 that was more hit&miss.

For the Low temperatures our average first frost is September 24th, but that's just the average. About half of the time we'll hold out until October without a night below freezing.

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