Summer of ’17 wasn’t hottest ever, but it was close
If you thought Calgary’s summer was warmer than usual, you’re not wrong.
In fact, a Calgary summer hasn’t been warmer than this since a young Audrey Hepburn charmed moviegoers in Breakfast at Tiffany’s, Please Mr. Postman by the Marvelettes topped the music charts and bus fares were only about 15 cents.
As crisper autumn winds blow through the city and leaves begin to fall from trees, Environment Canada says 2017 will go down in the record books as tied for the third-hottest summer since records started being kept in 1884, with an average temperature of 16.8 C recorded over the months of June, July and August.
Environment Canada meteorologist Brian Proctor said Calgary’s ascension up the ranks of historically sizzling summers was primarily due to a particularly sweltering July, which saw the mean temperature hit 18.3 C, well above the average monthly mark of 16.5.
“I think people in Calgary needed this summer as a respite from the wet summer they had in 2016,” Proctor said.
“But, really, it was that very warm July that seemed to push it into the record books.”
You don’t have to flip too far back in the calendar for the last time Calgary experienced a summer this balmy — the city experienced the same mean summer temperature in 2015. That was the hottest average temperature recorded since the same mark was set four decades earlier in 1970.
For Calgary’s hottest summer, with a mean temperature of 17.6, you have to go back a bit further to 1961. No. 2 on the list was set in 1919, with a mean temperature of 17.
Along with the eye-popping highs, Calgary also saw less rain than it would during a normal summer, with just 139.8 millimetres of precipitation, well below the seasonal average of 207.3 mm. However, Proctor noted the Calgary region was also mostly spared from the usual punishing summer hailstorms that skirted the city and instead ripped through Red Deer and parts of central Alberta.
The main culprit behind the historic heat wave, Proctor said, was a blocking pattern that hung over southern Alberta, redirecting the jet stream north and locking in the warm air for most of the summer months.
“Some would call it a big dome of warm air,” he said.
“The jet stream would just flow around and you would get these very protracted and extended dry periods.”
That immovable dome also meant air flowing into the city, particularly the smoky haze from massive forest fires in neighbouring B.C., would also linger, resulting in 2017 also going down in the record books as the smokiest recorded.
Weather historian Rolf Campbell, whorunstheYYCWeatherRecords Twitter account, has been dutifully recording the number of smoky hours in the city this year, which easily eclipsed the previous mark earlier this month.
As of Sept. 10, Calgary had recorded 321 hours of smoke, according to Campbell’s data, surpassing the previous high of 268 hours set in 1969.
Campbell, an IT expert who also plumbs historical weather data in Canadian cities as a hobby, also points out that his analysis of Environment Canada’s data shows that based on astronomical summer, from the day after the summer solstice to the day before the autumnal equinox, 2017 is actually the hottest summer ever recorded in Calgary.
“WhenusingEnvironmentCanada’s normal definition of mean temperature, but using astronomical summer, Calgary had its hottest summer ever,” he said in an email.
Campbell’s analysis found Calgary’s average temperature over that period between late June and late September was 16.89, outpacing the previous record of 16.74 set in 2012.
With summer now in the record books, Proctor said Calgarians can now brace for winter, which, because of a La Nina system developing in the equatorial Pacific, will likely be warmer than normal start to the season, before going into the deep freeze.
“We’re forecasting that December and January are going to be cooler than normal and a bit snowier than normal, too,” he said.