It's going to be a long, hot summer in Toronto, Environment Canada says

"We often say that, in weather, there is something called 'persistence' — what you see is what you are going to get," says senior climatologist with Environment and Climate Change Canada.

Sweltering temperatures expected to stick around through July, August

Toronto and surrounding regions have already seen more days above 30 C this summer than is typical for an entire year. (Mark Blinch/Reuters)

The heat wave currently gripping the Greater Toronto Area and most of southern Ontario won't be rolling on any time soon.

So far, there have been six consecutive days above 30 C in the GTA, and it's a "slam dunk" that the next three will be just as sweltering, says Dave Phillips, senior climatologist with Environment and Climate Change Canada.

And the federal weather agency records daily temperatures in the shade, he told CBC Radio's Metro Morning on Wednesday.

"You go out there and stand in the sun at Bay and Bloor (streets), and you can add another seven or eight degrees to that." 

While it won't be a record for the Greater Toronto Area, will be pretty close. In 1953, there were 12 straight days of temperatures above the 30 C mark, Phillips explained. 

"But that was at the end of August and into early September."

There have also been six straight "tropical nights," a term Environment Canada uses for nights where temperatures stay above 20 C. Statistically speaking, Toronto and surrounding regions would normally see one or two per year. Tuesday night was the warmest of 2020 so far, with a low of 23.1 C, Phillips added.

'Not even in the dog days of summer'

This summer has also seen scorching temperatures take hold earlier than usual.

Southern Ontario has already had 19 days above 30 C. In most years there are about 16, and last year had just 11 days with highs above 30 C. There have also been several days with recorded highs around 29.5 C, just cool enough to be excluded from the heat wave data.

"And we're not even in the dog days of summer. That is usually in about two weeks," Phillips told guest host Jill Dempsey. "This is clearly not something that we often see."

As for when it might end? 

The weekend is expected to bring a little relief, though daytime highs are still forecast to be in the high 20s. Then temperatures will likely shoot right back up into the 30s by the start of the next work week.

"We often say that, in weather, there is something called 'persistence' — what you see is what you are going to get," Phillips explained, adding that sweltering heat is expected to stick around throughout the rest of July and August.

Drought conditions

The other "worrying" element, he continued, are drought conditions. 

In the last 27 days, only a "thimbleful" of rain has fallen in the GTA. When rain has fallen, it's been sporadic.

"Everything is like a thunderstorm where it rains in your front yard but not your backyard. And that's not going to correct the situation at all," Phillips said.

"What we want is the kind of rain that would spoil your summer holiday. We need a slow, drenching, soaking rain —morning, noon and night — for three or four days" if plants and crops are to bounce back. 

Given the current heat, Phillips cautioned that it is important to check on vulnerable people, especially infants and the elderly, and seek out shade outside whenever possible.

The City of Toronto has opened a number of cooling centres that will remain accessible throughout the heat wave. Click here to find one near you.

With files from Metro Morning and Lucas Powers


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