Environment Canada issued in four provinces on Tuesday, including Ontario, Manitoba, Saskatchewan and Quebec.
Temperatures could reach the 30 C mark in parts of northwestern and northeastern Ontario, with the humidity making it feel closer to the mid-30s, Environment Canada says, with similar conditions expected in southwestern and southeastern Ontario.
The City of Toronto will keep until about midnight on Tuesday to help residents cool off during the heat warning.
Heat warnings remain in place across parts of , where wildfires have prompted additional air quality notices due to smoke.
Environment Canada has also issued an air quality statement for the area around Lytton, B.C., where a large wildfire has grown to .
Some communities in the province experienced over the weekend.
Dominion City, which is about 80 kilometres south of Winnipeg, had its hottest July 17 on record with temperatures reaching 34.2 C, beating the previous record of 32.2 C set in 1942.
McCreary, located about 200 kilometres northwest of Winnipeg, also set a record for that day with temperatures of 31.9 C, beating the 31.7 C record set just last year.
Shoal Lake, about 250 kilometres west of Winnipeg, recorded temperatures of 31.2 C. Its previous record for July 17 was 30.9 C in 2011.
In Saskatchewan, heat warnings are largely limited to the central and northern regions of the province, with daytime temperatures around 30 C expected, Environment Canada says.
Parts of Saskatchewan experienced periods of , including hail, heavy rain and intense lightning on Sunday.
Heavy rain overnight on Monday also caused flooding in parts of .
The heat and humidity could make parts of feel like 40 C or more.
A cold front moving through the province also may trigger showers and thunderstorms.
Across the pond, temperatures reached record-breaking levels in the United Kingdom, surpassing 40 C for the first time.
In Spain and Portugal, a heat wave has resulted in nearly 750 deaths, while wildfires have broken out in those countries and others in Europe.
With files from 麻豆影视, The Canadian Press and The Associated Press
