Parts of Ontario could experience temperatures that feel as high as 45 degrees Celsius with the humidex this Canada Day weekend, while southern Quebec and the Maritimes are also bracing for high heat.

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Environment Canada is warning of “extreme heat” all weekend for much of Ontario, with cities like Ottawa, Toronto and Barrie expected to reach 35 C or higher on Saturday.

In Toronto, it could feel as hot as 45 C on Saturday, once the humidex is factored in.

“What we’re seeing in parts of central Ontario are probably very close to record amounts of humidex,” said David Phillips, senior climatologist from Environment Canada, noting Canada Day revelers on Parliament Hill in Ottawa could witness the hottest July 1 in 55 years.

The humidex, which describes how hot and humid the weather feels for the average person, is expected to be higher in some places than it has been in years.

“We’ll just clobber the humidex,” Phillips said.

The temperatures will be “sultry” and “oppressive,” he told CTV Barrie on Thursday. “You’d have to go to the Caribbean, or India or some tropical countries to see that kind of a situation,” he added.

Phillips suggests the more heat-sensitive of the population take it easy. Find a cool space, a body of water to swim in, drink lots of liquids and wear your linen, if you’ve got it, he said.

Montreal humidex could hit 40 C

Parts of Quebec are also experiencing what Environment Canada calls “a significant heat event.”

“Sunday and Monday will be especially humid, with highs in the low- to mid-thirties and humidex values exceeding 40,” says a special weather statement issued for Metro Montreal and Laval.

“During this event, overnight lows will remain near 20 degrees Celsius and will give only little or no relief from the heat,” the statement goes on. “This heat wave will persist through next week.”

Montreal is forecast to reach 36 C on Saturday, and it could feel more like 39 C that day. Some public pools in the Montreal area will have extended hours to help people cool off.

Maxime Roy, from the city’s public health department, recommended that people avoid physical activity outdoors and stay hydrated.

“Don’t wait until you’re thirsty to drink water,” Roy said.

Maritimes bracing for warm, humid airmass

Meanwhile, Environment Canada has issued special weather statements for much of the Maritimes, including Halifax, Saint John and Moncton.

“A warm and humid airmass will gradually settle over the Maritimes this weekend and persist into early next week,” the statement reads.

“The hottest temperatures and highest humidex values will likely be on Monday and Tuesday,” the statement goes on.

Humidex values are expected to reach the mid-to-high 30s, according to CTV Atlantic Chief Meteorologist Kalin Mitchell.

With reports from CTV Barrie, CTV Ottawa, CTV Atlantic and CTV Montreal