Relief from sweltering heat on its way for many parts of the country

Globe and Mail

a day ago

Sweltering heat is expected to break in the coming days for many Canadians after Monday's scorching temperatures broke dozens of daily heat records across the country.
Around 51 daily heat records were broken across the country on Monday with many regions recording temperatures in the mid-30s, said Christy Climenhaga, a scientist with Environment Canada.
'When numerous (temperature) records are falling, that indicates that it is more of a notable heat event,' Climenhaga said in an interview Tuesday.
Relief is coming first for southern British Columbia, where a multi-day heat wave is expected to end on Tuesday or Wednesday, as temperatures return to the seasonal mid-20s in many regions.
Monday's temperatures broke or tied daily heat records in nine regions in the province, according to Environment Canada, six of which were located on Vancouver Island.
That included the Victoria area, which saw temperatures reach 33.8 C, nearly two degrees warmer than the 31.9 C record set in 1990.
New heat records stretched as far north as Pemberton on the mainland, with the weather agency reporting temperatures of 37.4 C, beating the 1977 daily temperature record by a small fraction.
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Hot conditions are expected to continue through Wednesday in southern Ontario, stretching north past Lake Huron and Georgian Bay and east through southern Quebec.
Ontario saw 10 new daily heat records broken or tied yesterday in areas including Algonquin Park, Goderich, Parry Sound and Bancroft, Climenhaga said.
While cooler temperatures are expected to sweep through the area by Tuesday evening with the heat warning coming to an end by Wednesday, Climenhaga said southern Ontario should still expect temperatures in the 30s through the end of the week.
'Toronto is still going to be hot through much of the week, but perhaps below the heat warning criteria,' she said.
In the Maritimes, high temperatures are expected to remain through to Wednesday, while parts of Newfoundland will see similar conditions breaking on Thursday or Friday.
Dozens of daily heat records were shattered across the Atlantic provinces on Monday, according to the national weather agency, surpassing temperature records previously set as far back as the late 1800s.
Miramichi, N.B., broke a more than 150-year-old temperature record with the heat climbing to 37.6 C Monday, just under one degree below a record set in 1876. Fredericton also surpassed a daily high of 35 C from 1893 by a tiny fraction.
Monday's heat in some Newfoundland and Labrador regions even set new monthly extreme temperature records for August, according to Environment Canada.
La Scie, N.L., set a new monthly high of 31.5 C yesterday, breaking a previous August heat record of 31 C set on Aug. 7, 1990. Similarly, the Labrador region of Mary's Harbour broke a monthly record from Aug. 6, 1990 by almost two degrees.
Amid the heat, an Agriculture Canada update shows Nova Scotia, eastern Newfoundland, southeastern New Brunswick and portions of Prince Edward Island shifting into moderate and severe drought conditions over the past month, with rainfall levels plummeting to 60 per cent of normal levels in Halifax.
Climenhaga said an atmospheric upper ridge has formed in the atmosphere over the east coast, trapping the heat and preventing the rain from getting through.
'You get heat building under that ridge that will give you prolonged periods of hot and dry weather,' she said.
In eastern Ontario, water conservation efforts are underway with rainfall down 40 per cent and a citywide burn ban in place for Ottawa.
Agriculture Canada reported that fully 71 per cent of the country was classified as abnormally dry or as being in a moderate to extreme drought by the end of July.
It only takes a couple days of hot and dry weather for wildfire risk to grow, Climenhaga said, and that extended periods of extreme heat can 'increase risk and volatility very quickly.'
Data show this year's wildfire season is already the second-worst on record.
Climenhaga said British Columbia and the Prairies are expecting to see 'some decent rainfall' to mark the end of the dry spell, while the Maritimes should see 'showery rainfall here and there' toward the end of the week.
But she said a single rain shower won't mark the end of wildfire and drought seasons, noting that consistent rain over long periods of time is important to reduce risks.
'When you look at prolonged dry weather and you've got a lot of fires burning, one dose of rainfall isn't necessarily a magic bullet to solve everything,' she said.
'If you've got a good amount of rainfall but then the dry, hot weather comes back, you could be right back to where you started.'