Much of Western Canada could see temperatures rising to the mid-30s in coming days, while Central Canada enjoys a reprieve after a bout of record-setting heat.
Environment Canada is forecasting temperatures in the low 30s from Edmonton to Regina on Monday, while Winnipeg will see a high of 29 C. Even in Yellowknife, temperatures will push 30 C.
The heat wave is "great news for Calgary if you like it hot for the Stampede," said CBC meteorologist Johanna Wagstaffe, although there is a risk of a thunderstorm late in the afternoon or evening.
The hot weather is expected to settle over the Prairies for several days and may bring highs reaching 35 C.
Elsewhere, parts of northern Ontario could be in store for thunderstorms Monday, with a slight chance the storm systems could reach south of Georgian Bay and west of Lake Ontario. Temperatures will hover in the mid-20s across much of the province, with slightly warmer weather from London to Windsor in southwestern Ontario.
The cooler weather in Ontario follows a heat wave that set 11 temperature records on Friday alone.
British Columbia is also experiencing persistent heat following a weekend of record temperatures. Environment Canada has issued a severe thunderstorm watch for parts of the B.C. Interior, stretching from the Okanagan Valley to Peace River. Temperatures in that area will remain in the high 20s, while in Vancouver and Victoria it will be 23.
Parts of southern B.C. are also blanketed by smoke from wildfires in Colorado and Russia, and provincial fire officials say the smoke could linger for up to a week. Environment Canada says there is a moderate health risk from the poor air quality, and people with heart and lung problems should avoid strenuous outdoor activities.
In Quebec and along the East Coast, it will be mainly sunny on Monday with temperatures hovering in the low to mid-20s.
Meanwhile, Americans will get a reprieve from heat that has blanketed a swath of the United States, as temperatures begin approaching normal from the Midwest to the East Coast.
National Weather Service meteorologist Andrew Orrison said a cold front will move through the South and the mid-Atlantic bringing thunderstorms and showers.
He said temperatures will drop to a more normal range — "still fairly warm," Orrison said, but not as hot as it has been there recently.
The cooler air began sweeping southward Sunday in the eastern half of the U.S., following a heat wave that has been blamed for at least 46 deaths across the country.
In Tennessee, the third heat-related death of the year was a 62-year-old woman found dead in her home. She had a working air conditioner, but it was not turned on.
Deaths have also been reported by authorities in Maryland, Ohio, Pennsylvania and Wisconsin.