Humidex temperatures in Toronto could reach the low 40s this week, according to an Environment Canada heat warning for most of southern Ontario.
Temperatures would range between the high 20s to low 30s, reaching over 40C when humidity is factored in.
The warning said the high temperatures will begin Tuesday afternoon and could last for two to three days.
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“These hot and humid conditions will begin to end from west to east Wednesday night,” the warning said.
Similar warnings were issued across the Greater Toronto Area and southern Ontario. Warnings stretched from Windsor and the United States border in the west across into Quebec.
Heat warnings are also in effect as far north as Bracebridge, Ont., with some reprieve in cottage country. Huge swathes of northern Ontario, including Sault Ste. Marie and Fort Frances are also set to receive extreme heat.
The weather agency issued a reminder to stay hydrated and in a cool place.