MONTREAL - Some like it hot, but this week may prove to be too much.

For the second day in a row, Montreal was subject to extreme heat, with temperatures reaching a record-setting 35.2 Celsius Thursday afternoon.

That's the hottest temperature ever recorded in Montreal for July 21. The previous high, set in 1955, was 35.0 C.

Environment Canada issued a high heat and humidity warning for most of southern Quebec Thursday along with a severe thunderstorms warm.

The heat wave that slowly rolled across the continent moved into the region Wednesday morning and is expected to stick around for several days, with forecast highs being at least 30 degrees until the weekend.

But it's the extreme humidity that will send people to the air conditioner.

Environment Canada has issued high heat and humidity warnings for everywhere in Quebec south of the capital, saying humidex values will be over 40 for the rest of the week.

The heat wave brings with it a chance of thunderstorms, especially for areas north of the St. Lawrence river.

People with chronic lung conditions, senior citizens, and others vulnerable to health problems are being advised to stay out of the heat, drink lots of water, limit strenuous activity, and take advantage of shady areas and air conditioning.

Doctors say that anyone showing signs of heat stroke, such as nausea, dizziness and a headache, should get medical help immediately.

Record-setting heat in southern Ontario

The heat wave is flirting with record highs across Eastern and Central Canada.

In Windsor, Ont., the temperature was expected to reach a scorching 39 Celsius Thursday, making it the hottest city in the country.

Environment Canada released a special weather statement for the region on Thursday, warning residents that a "sultry tropical air mass" will make its way across all of southern Ontario by the afternoon.

If the temperature in Windsor matches what is predicted, the forecast will come close to breaking the city's highest-ever temperature of 40.2 C set on June 25, 1988.

And in Hamilton, the mercury is expected to reach 37 C, just below the city's old high of 37.4 C.

Meanwhile, in Canada's largest city, officials reissued an extreme heat alert warning Torontonians to try and stay cool as the temperatures continue to climb. Residents woke up to a record morning high of 26.6 C.

Temperatures in the city are expected to climb to a high of 38 C, but baseball fans with tickets to Thursday's Blue Jays game at the Rogers Centre will get some reprieve from the sweltering temperatures as the retractable roof will be closed for the game.

Across Ontario, heat alerts have been issued in several areas including the Niagara region, Waterloo and Cornwall. In Ottawa, forecasters predict the mercury will likely hit 34 C and 31 C in Fredericton.

Environment Canada's senior climatologist Dave Phillips told CTV's Canada AM on Thursday that the heat dome, a hot, stagnant high-pressure area, is presently hanging over central parts of Canada and keeping cooler or wetter weather out.

"It's almost like a bully, it just doesn't move," he said. "Any type of cold, fresh, Canadian cold waves are just blocked from coming in."

According to an Environment Canada warning preparedness meteorologist, the heat dome phenomenon happens every few summers.

"Every day it gets hotter and hotter," Marie-Eve Giguere told The Canadian Press. "It gets heat from the sun and this sort of hot dome air is getting hotter and hotter and this is what's creating these high temperatures."

The dome is currently sitting over much of the United States. It spread up to Western Canada over the weekend, covering large swaths of the country and pushing the temperatures to scorching highs in the Prairies.

On Tuesday, Winnipeg was baking under a high of 34.4 C and Regina under 31.9 C.

Looking ahead, the 10-day forecast predicts above-normal temperatures from eastern Alberta through to Prince Edward Island.

Phillips also noted that what's remarkable about this prologned heat blast is that temperatures aren't dipping off overnight.

with files from News Staff