Little relief is in sight as Eastern Canada continues to swelter under scorching temperatures and high humidity, causing persistent heat and severe thunderstorm warnings across the region.

Temperatures reached as high as 34 C in the Greater Toronto Area Saturday afternoon. It felt like a blistering 44 C with the humidex. Montreal experienced similar heat, with humidex values reaching between 40 C and 43 C.

The hot and humid weather, caused by a so-called “heat dome,” stretched across southern and northern Ontario, southern Quebec, Nova Scotia and New Brunswick.

Even parts of the Northwest Territories were issued heat warnings with temperatures reaching as high as 30 C, according to Environment Canada.

The main cause for a heat dome is a long lasting area of high pressure, combined with the lingering effects of La Nina, according to the U.S. National Oceanic Atmospheric Administration (NOAA). In laymen’s terms, it gets hot, and stays hot.

"When high pressure high up in the atmosphere is present it can trap warm air at the surface - it basically acts like a lid," said CTV News meteorologist Kelsey McEwen, adding that the current heat wave builds on weather patterns established from La Nina during the previous winter. La Nina is when sea surface temperatures in certain parts of the Pacific Ocean are cooler than normal.

The heat wave is expected to last until Sunday, when temperatures will ease below 30 C.

Western Canada will then face sweltering weather, according to McEwen, who notes that Calgary is expected to see highs of 28 C by Tuesday.

Hotter, longer heat waves expected in the future

Climate change means that temperatures could be even more unbearable in the future, according to Miriam Diamond, earth sciences professor at the University of Toronto.

“The important point here is that this is not the new normal,” Diamond told CTV News Chanel.

“The climate is continuing to heat up. So, we’re really hot right now and the future holds even higher temperatures for longer, more prolonged periods.”

But Diamond says that Canadians can’t just simply acclimatize to warmer temperatures.

“There’s a limit to what the human body can endure—and that’s not going to change,” she said.

“We’re not just going to air condition ourselves to a solution here.”

Tips for staying safe in high heat

Extreme heat affects everyone, but Environment Canada cautioned that young children, pregnant women, people with chronic illness, older adults, and people working or exercising outdoors face greater risks in the hot weather.

The public is advised to never leave people or pets inside a parked car, and to stay hydrated and find shade, especially if they feel dizzy, overly tired, unwell, nauseous, or have a headache.
Staying hydrated is particularly important at night, according to Diamond.

“The important thing to note is that it’s the nighttime temperature is of the greatest concern. It’s when the nighttimes don’t cool off that it causes the greatest health effects,” Diamond said.

“Your body normally cools itself by sweating, but when it’s so humid the sweat doesn’t evaporate from your body and cool your skin,” she explained.

For a full list of heat alerts, you can visit Environment Canada’s website.

- With files from Solarina Ho