Scorching summer heat hits Canada, but won't touch records set by the 2021 heat dome

Sweltering temperatures stretching from British Columbia to the Ontario border has prompted hundreds of heat warnings, but it's not as intense at the deadly 2021 heat dome in B.C., says a national warning preparedness meteorologist.

Jennifer Smith with Environment and Climate Change Canada told a news conference Monday that while the "epicentre" of the heat is located in Northern California, it is expanding north and east this week, where it is expected to linger.

An unrelated heat wave has meanwhile sent temperatures into the 30s in Atlantic Canada.

"Above normal temperatures developed across southern B.C. over the weekend. The heat will continue there and expand east, affecting Alberta and southwestern Northwest Territories today, Saskatchewan by Tuesday and spreading into Manitoba by Wednesday," Smith said.

She said the heat event will be "significant and impactful" but it does not compare to the 2021 heat dome that surpassed heat warning thresholds by "a significant margin."

"That was truly an anomalous and extreme heat wave," Smith told the conference. "The highest temperatures forecast for this event are expected to be lower for the areas that saw the worst heat in 2021."

But, she noted the 2021 heat dome did not impact Saskatchewan and Manitoba.

"With the current heat event, several daily records may be broken across the region throughout the event, but all-time records should not be threatened."

In British Columbia, temperatures in the province’s southern Interior are forecast to climb into the low 40s.

The weather agency says the scorching temperatures in B.C. are caused by a ridge of high pressure, with heat warnings covering much of the southern part of the province, including Metro Vancouver. On Sunday, more than 20 daily heat records were broken.

"High pressure causes air to sink and dry out, reducing cloud cover and leading to hot temperatures," Smith explained.

She warned the hot and dry conditions heighten wildfire risk, "particularly where there are existing fires or there is a precipitation deficit such as in northeastern B.C., northern Alberta and the Northwest Territories."

Armel Castellan, another meteorologist with Environment Canada, said B.C. is "definitely seeing its warmest temperatures over the next couple of days." He said the weather office is now working with the BC Wildfire Service and it will meet with emergency management officials in the province to prepare for the risks.

In the Prairies, temperatures in some parts of Alberta are forecast to reach about 35 C by Wednesday. Heat warnings were up Monday across most of the province and into Saskatchewan, where daily highs in Regina are expected to hover around 30 C for the whole week.

The tiny community of Fort Liard, in the southwestern corner of the Northwest Territories, is forecast to hit 30 C until Wednesday, well above its average high of 23 C.

Because this is the first widespread heat event of the year in Western Canada, Smith said health officials are warning of the risks, saying people may not be acclimatized to the hot weather.

"This warm spell is likely to linger into next week, particularly across southern B.C. and the Prairie provinces, though it's a bit early to offer a high confidence forecast this far into the future," she said.

"But, with many outdoor events ongoing — for example, the Calgary Stampede or the Winnipeg Folk Festival — it's encouraged to take extra precautions against the heat, drink lots of water, stay in the shade and arrange for regular checkups on family members, neighbours and friends in case they may need help."

Smith noted Ontario is right on "the fringe" of the heat wave.

"That ridge is essentially going to be retreating south as it transitions east," she explained. "I would expect some warmer temperatures to touch on northwestern Ontario before that ridge fully moves south and retreats back into the United States."

Daytime highs around 30 C are forecast across much of Atlantic Canada, with humidex readings close to 40 in New Brunswick and Nova Scotia.

Meanwhile, the European climate service Copernicus is reporting the global temperature in June hit a record high for the 13th straight month. The agency said June was also the 12th consecutive month that the world was 1.5 C warmer than the pre-industrial average. Most countries agreed to try to limit global warming to 1.5 C as part of the 2015 Paris climate agreement.

Eastern Canada, which was hit by an intense heat wave in mid-June, is one of the regions where temperatures were most above average.

June was also the 15th month in a row of record-high sea surface temperatures, according to Copernicus.

A strong El Niño weather pattern helped drive the spike in global temperatures over the last year, according to the United Nations weather agency. But the World Meteorological Organization warned last month that the last nine years have been the warmest on record even with the cooling influence of a multi-year La Niña event.

“The end of El Niño does not mean a pause in long-term climate change as our planet will continue to warm due to heat-trapping greenhouse gases,” said WMO deputy secretary-general Ko Barrett in a June statement.

Later this week, remnants of Hurricane Beryl, which devastated parts of the Caribbean last week, are forecast to move into Ontario and Quebec, bringing rain and a risk of thunderstorms.

This report by The Canadian Press was first published July 8, 2024.

The Canadian Press