Sweltering heat topples 11 Ontario records

Heat and humidity blanketed parts of Central Canada Friday, with soaring afternoon temperatures breaking 11 daily records for Ontario, including in Toronto and Ottawa.

The sweltering weather returned after a brief reprieve on Thursday from the heat and humidity, while those in the West are bracing for scorching heat forecast for the coming days.

'Canada is not the Great White North that it used to be.' —Dave Phillips, Environment Canada senior climatologist

In south-central Ontario, temperatures felt like the mid- to high-40s and humidex advisories were reissued for the region.

"We'll probably see Toronto, Hamilton, Wiarton and Sarnia break temperature records for July 6," CBC meteorologist Johanna Wagstaffe said. "And we have seen daily temperature records break throughout the week."

With the humidity factored in, it was expected to feel a lot hotter — in the 40s.

By the late afternoon, the heat record was broken in Toronto when temperatures at Toronto's Pearson International Airport hit 36.3 C, smashing the hottest recorded July 6 from 24 years earlier. The 1988 high was 34.7 C.

"It will get worse before it gets better. It's the kind of heat that if you're sitting still, not doing anything, in the shade, you're going to feel it. It's oppressive," Wagstaffe said.

Ottawa also broke its daily record, according to CBC Ottawa weather specialist Teri Loretto. Friday's 34.4 C high beat the 2010 record of 34.1 C.

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Humidex advisories were extended east to Ottawa and Montreal on Friday for the first time this week.

According to Environment Canada, the 11 temperature records set in Ontario on Friday were recorded at:

• Burlington Lift Bridge, 35.3 C (previous daily high of 33.0 C set in 2010).
• Caribou Island, 20.1 C (previous daily high of 19.8 C set in 2000).
• Cobourg, 33.2 C (previous daily high of 28.6 C set in 1999).
• Great Duck Island, 25.9 C (previous daily high of 21.9 C set in 2002).
• Mount Forest, 31.4 C (previous daily high of 30.3 C set in 2010).
• Ottawa Macdonald-Cartier airport, 34.5 C (previous daily high of 34.1 C set in 2010).
• Point Petre, 27.3 C (previous daily high of 27.2 C set in 2010).
• Port Weller, 33.4 C (previous daily high of 29.3 C set in 1993).
• Southeast Shoal, 31.3 C (previous daily high of 28.2 C set in 1999).
• Toronto Pearson airport, 36.3 C (previous daily high of 34.7 C set in 1988).
• CFB Trenton, 33.6 C (previous daily high of 31.4 set in 2010).

"Canada is not the Great White North that it used to be," said Environment Canada senior climatologist Dave Phillips, noting that climate change over the past half-century has diminished what's known as the "diurnal difference" — the temperature range between the daily maximum and minimum.

"It's the difference between the daytime high and the nighttime low. In the past, that was quite a wide difference, and so you'd get a hot day, but you can recover at night. What we're seeing now is that's narrowing," Phillips explained. "There's less of a difference between what happens during the day and what happens at night."

Frizzy hair

As for why some people might be experiencing bad hair days amid the sticky weather, CBC meteorologist Nick Czernkovich said humidity can cause hair to lengthen up to three per cent due to the atmospheric moisture.

"If your hair is frizzy, this is why," he said.

Another byproduct of the heat wave is the strain on power systems. People in Toronto were being asked to ease off on their air conditioning after a power outage in a large area of the downtown Thursday night.

Toronto Hydro said its system was overloaded because of the hot spell. More than 6,000 homes and businesses lost power after an electrical substation overheated. Fire crews had to clear smoke out of the building before they could assess the damage.

Hydro workers restored power early Friday morning, but officials warn the hot evenings aren't allowing the system to cool down, so there could be more problems.

A weak cold front will slide southward toward the end of the day for the Lower Great Lakes, so conditions will be noticeably drier for Saturday, with even drier air on the way early next week.

Just as Central Canada gets some relief from the humidity, it will be the West's turn to swelter with the same hot air mass that has been affecting millions of people the U.S over the past week.

"This high-pressure dome which has been anchoring the heat in the U.S. is shifting and will move into the western half of Canada," Wagstaffe said.

"They will feel it in the B.C. Interior, where by the end of the weekend we'll be talking temperatures in the 40s for parts of the Okanagan Valley."

"The heat will start to build through Alberta tomorrow and Saskatchewan for the weekend. They're looking at an extended period of temperatures in the 30s."

Central U.S. continues to swelter

Meanwhile, there has been no relief from a record-setting heat wave that has blanketed the Central United States for several days.

The U.S. National Weather Service reported late Thursday the mass of hot air was slowly moving into the mid-Atlantic states and Northeast.

Excessive-heat warnings were issued for all of Illinois and Indiana, as well as parts of Iowa, Minnesota, Wisconsin, Missouri, Kentucky, Ohio and Michigan.

Lack of electricity will compound the misery for many in the storm-ravaged East as higher temperatures move in.

Late Thursday, nearly 230,000 people in West Virginia and more than 83,000 in Virginia were without power.

Maryland, which still had more than 45,000 without power, reported Thursday that eight people had died of heat-related causes in recent days.

More than 3,000 temperature records have been shattered in the U.S. this past week. Meteorologists say the heat will ease Saturday in the cities of Chicago, St. Louis, Nashville, Atlanta, Washington and New York.