Why this hot stretch isn’t considered a heat wave
Ryan Flanagan, CTV Kitchener
Published Monday, June 12, 2017 4:51PM EDT
Last Updated Monday, June 12, 2017 6:44PM EDT
Most of southern Ontario remained under a heat warning Monday afternoon, with some areas seeing their hottest temperatures of 2017 thus far.
In Waterloo Region, temperatures topped 30 C for most of the afternoon. The high-water mark may have come in the 3 p.m. hour, when a mark of 30.7 C was recorded at the Region of Waterloo International Airport.
It was the third straight day of temperatures above 30 C, following highs of 30.3 C on Saturday and 31.4 C on Sunday.
It was hot enough to have splash pads full, ice cream shops busy and air conditioners running at full blast.
What it wasn’t, though, was a heat wave.
Environment Canada has historically had strict definitions for the term. While the exact parameters vary from region to region, the idea behind them is the same – not just hot weather, but unusually hot weather.
For an official heat wave to happen in southern Ontario, a community would have to experience temperatures of at least 32 C on three consecutive days.
While three straight days of 30 C is more than hot enough for a lot of people – especially with the sort of humidity we’ve been seeing – it isn’t hot enough to meet that definition of a heat wave.
Waterloo Region came close to experiencing a true heat wave on several occasions last year, including narrowly missing out when the mercury refused to rise past 31.7 C on Aug. 12, the third day of the heat event.
To find a bona fide heat wave in this area, you have to go all the way back to July 2013. From July 17 to July 19, daytime highs of 32.6 C, 32.8 C and 33.1 C were recorded.
Temperatures are expected to cool off significantly as the week goes on.
Environment Canada’s forecast highs for Waterloo-Wellington are 27 C on Tuesday, 24 C on Wednesday and 21 C on Thursday.
As a result, it will be at least a little while longer before our area sees its first heat wave since 2013.