May heat wave foreshadows 'hotter future' for Western Canada, experts say

An unusual May heat wave that has sent temperatures soaring 10 to 15 degrees higher than normal across parts of Western Canada should be seen as a warning to prepare for dangerous hot spells outside the normal summer timeframe, researchers say.

The unseasonably hot temperatures that began Friday are persisting throughout British Columbia and Alberta this week, raising wildfire and flood risks and triggering heat warnings and advisories.

While the current heat isn't as severe as the B.C. heat dome in June 2021 that killed hundreds of people, scientists say such prolonged high temperatures in May are highly unusual, and Western Canada will likely see more such heat waves in coming years.

Joseph Shea, an associate professor in environmental geomatics at the University of Northern British Columbia says Western Canada residents “need to adapt to a hotter future.”

He says the region would be looking at “a similar heat dome situation” had the weather pattern creating the temperature spike happened in June or July.

Environment Canada has issued a heat warning for most of the northern half of Alberta starting just north of Edmonton, covering communities ranging from Grande Prairie and High Level to Fort McMurray and Cold Lake.

A warning has also been issued for B.C.'s north coast, including Kitimat and Terrace, with high temperatures in the forecast stretching into the long weekend.

The warning from Environment Canada says a plume of hot air is to remain in place over parts of B.C. through Thursday, bringing daytime highs to near 30 C and overnight lows near 15 C.

Much of the rest of the B.C. coastal and Interior regions remain under special weather statements after temperatures spiked above 30 C in many communities on the weekend.

Several broke temperature records, including Agassiz, which hit 31.6 C, and Fort Nelson, which saw 28.1 C.

Andreanne Doyon, an assistant professor in the School of Resource and Environmental Management at Simon Fraser University, says “we are not supposed to have heat like 10 to 15 degrees hotter than average in May.”

“We know that things like heat waves are going to be more frequent, they are going to be more severe and they're going to happen at times of the year where they previously haven't,” she says.

Doyon says she is especially concerned about urban centres such as Vancouver, Calgary and Edmonton, where infrastructure such as pavement and concrete absorbs more heat than foliage and natural landscapes.

“Heat waves are sometimes referred to as the deadliest of natural disasters because they are something that people don't focus on,” she says.

“With the wildfires that B.C. and Alberta are experiencing right now, the photos are very extreme, and it's really tragic where we haven't been able to communicate the severity of heat waves and those impacts in the same way.”

The Peace River Regional District says there was “significant fire activity” on Saturday that necessitated evacuation orders and alerts.

B.C.'s River Forecast Centre also issued several high streamflow advisories for the Skeena River, the Upper Columbia and East and West Kootenay rivers and others, as the high temperatures accelerated the spring snow melt.

People are being warned to stay away from fast-moving waters and unstable banks.

B.C.'s Interior has been particularly hard-hit by flooding and fires this spring, including Cache Creek, where flooding earlier this month forced people from their homes and damaged highways.

Cache Creek Mayor John Ranta says the provincial government has started working on part of Highway 97 that was washed out due to flooding but he's not sure whether returning that area to pre-flood condition will be enough to address future flooding concerns.

He says Cache Creek has flooded four of the last five years and some sort of permanent solution is needed.

“I don't know exactly what that is. People have talked about a bridge, people have talked about just forget the bridge and leave a channel there for the river to go through and don't use that road anymore, those sorts of ideas,” he says.

He says the town is planning to start collecting donations for people impacted by the flooding who could not afford expensive overland flood insurance.

This report by The Canadian Press was first published May 15, 2023.