Extreme weather conditions in many parts of the country on Monday prompted heat warnings from Environment Canada for parts of southwestern Quebec and tornado warnings for southern Saskatchewan. The extremely hot, humid conditions will linger over parts of Canada all week, said CBC meteorologist Ross Hull.
By early Tuesday morning, an Environment Canada warning about the heat remained in effect for parts of Southern Quebec including Quebec City, Montreal, Laval and the Eastern Townships. In Saskatchewan, earlier thunderstorm and tornado warnings were lifted.
Peak humidex levels in the low 40s are expected for the next several days with another moisture-laden air mass expected to move in, according to Environment Canada.
That combination could be particularly hard on the elderly and people with chronic respiratory and heart conditions, Hull said. "Avoid strenuous exercise and stay well hydrated."
Why is it so hot?
July and August tend to be our hottest and most humid time of the year, said Hull. Record high temperatures were set Monday in Quebec and Atlantic Canada. In Halifax, the temperature hit 32. Quebec City and Badger, N.L., also hit record temperatures, cracking 31, and in Bathurst, N.B., it was a scorching 35.8.
"I wouldn't be surprised to see more high temperature records broken over the next couple of days," said Hull.
A ridge of high pressure spinning off the U.S. east coast is behind the hot, sticky air mass stretching from Northern Ontario to Newfoundland.
"High pressure often means sinking air and when that air sinks it heats up even more," said Hull.
Definitions as to what constitutes a heat wave differ by province but in Ontario, it's three days of temperatures above 32.2, before factoring in the humidex.
This ridge is going to take its time to clear out, so for some areas of Central Canada there may not be any relief until later this week.
Humidex values are expected to fall below 40 in Southern Ontario and Quebec by Friday.
That relief will come in the form of a cold front and we will have to be on the lookout for some strong storms associated with this cooler air mass clashing with the humid, hot one in place now, said Hull.
Storms over the Prairies
A extreme difference in air masses over Alberta and Saskatchewan — where cooler air from the west is clashing with hot air pushed from the east — could "spark up" some severe thunderstorms over the Prairies, Hull said.
"All the right ingredients are in place" including a moist, unstable air mass coming in from the U.S. and a dry line associated with a low-pressure system moving in from Alberta, said Hull. "When those two air masses collide it could make for an extremely dangerous situation."