The sweltering weather continues Saturday with several parts of Canada under heat warnings.

It's the hottest day of the year so far for Toronto, said Environment Canada meteorologist Sherry Williams, among other parts of southern Ontario.

The Greater Toronto Area has daytime highs of 34 C, though it will feel more like 44 with the humidex.

The evening might not bring much relief — the overnight low will hover around 22, but it will still feel like over 30 throughout the night.

It should cool down the GTA on Sunday, Environment Canada says, as humidity drops and temperatures fall into the mid to high 20s.

There's hot and humid weather in several parts of Ontario, southern Quebec, Nova Scotia and New Brunswick, the agency warns.

Southern Quebec and Ontario have temperatures in the 30s, with humidex values reaching the upper 40s farther south.

Environment Canada issued heat warnings for several parts of Canada on Saturday. This image was taken from the agency's website early Saturday afternoon. (Environment Canada)

It's also the hottest day of summer so far for Ottawa and Windsor, said Williams, and it's likely the same for other places in southern Ontario.

As of 2 p.m. Ottawa was "winning" the heat contest in Ontario with a humidex of 46, Williams said.

But Ontario temperatures could still climb another few degrees by the end of the day, she said.

"I don't think these are record-breaking temps, but they're pretty close," said Williams. "And it's very widespread."

As of late Saturday afternoon, there were also severe thunderstorm watches and warnings in several parts of southern Ontario and Quebec, as well as Fort Nelson, B.C., and parts of the Northwest Territories.

The huge blob of hot air that has blanketed several regions is known as a "heat dome." The heat was also strong on Friday, with the humidex as high as 42 in Toronto and reaching 47 in Sarnia.

Parts of northern Alberta and the Northwest Territories are also under heat warnings, with temperatures reaching 30 C.

Heat warnings different across country

The threshold for heat warnings changes in different parts of the country, said Williams.

Warnings are based on typical temperatures in each region and people's tolerance for hot weather, she said.

"Someone up in Timmins wouldn't be as used to the heat as someone in Windsor," Williams added.

Parks Canada crews opening canal locks. Friday’s high was 32.7°, making it the hottest day of the year so far in Ottawa. At 8am, it’s already 24° w/a humidex of 33! Heat Warning still in effect. Another scorcher. High 32°. Mix of ☀️&☁️w/a pm ⚡️/☔️ around WSW 20+ <a href="https://twitter.com/hashtag/ottnews?src=hash&ref_src=twsrc%5Etfw">#ottnews</a> <a href="https://t.co/yMewIhz4Gi">pic.twitter.com/yMewIhz4Gi</a> —@BlacksWeather

It's been a hot couple of days for parts of Canada.

"When you go outside, you feel like you're in the water because it is so humid," said meteorologist Julie Deshaies, speaking to CBC Montreal earlier in the week.





In Nova Scotia and New Brunswick, humidex values could be as high as 39 in parts of the province Saturday.

Environment Canada is reminding people to check in on loved ones, drink plenty of water and never leave people or pets in a parked vehicle.

The Ontario SPCA called on pet owners to take extra precautions over the next several days to keep their pets cool and safe.

The massive heat wave has also enveloped the U.S. Midwest and has pushed into the Northeast, ushering in temperatures that could top 38 in Washington and prompting utilities to take steps to prevent power outages.