Environment Canada has issued heat warnings for parts of Vancouver Island and inland sections of coastal British Columbia as the province braces for a heat wave.

The weather agency says a high pressure ridge building over the west coast will bring “very high temperatures” starting Friday and stretching into next week.

The first series of warnings spans eastern Vancouver Island, including Courtenay, Camplell River, Duncan, Nanaimo, Fanny Bay and other nearby communities.

The bulletin says daytime highs are expected to hit the low 30s in those areas with nighttime lows of around 16 C.

Another warning covers inland sections of the north and central coast, including Kitimat and Terrace, where the weather agency says daytime temperatures near 30 C are expected to persist from Saturday until Tuesday night.

Environment Canada says the heat poses a “moderate” risk to public health before the forecast returns to more seasonal temperatures later next week.

“Right now, it looks like [next] Wednesday is the day for a change in the airmass,” said Armel Castellan, a warning preparedness meteorologist with the agency.

He said the province is divided into five regions based on their typical climatology, and each region is subject to different criteria for triggering a heat warning.

In the northwest, that’s two days or more with daytime highs of 28 C or higher and overnight temperatures of 13 C, Castellan said in an interview.

But temperatures in parts of the southern Interior must hit 35 C for two days with an overnight low of 18 C in order to trigger a heat warning.

“Vancouver itself would be at 29 degrees for two days and 16 degrees overnight,” Castellan said of the heat-warning criteria in the province’s most populous city.

A special weather statement is also in effect for Metro Vancouver and the Fraser Valley, where above-average temperatures are expected well into next week.

The forecast for Vancouver projects daytime highs of 26 C on Sunday and Monday.

Environment Canada’s forecast says the mercury in Kamloops, B.C., is expected to hit 40 C on Monday and Tuesday, followed by 39 C on Wednesday.

In the northern community of Fort Nelson, B.C., daytime highs between 28 C and 30 C are expected from Sunday to next Wednesday. The entire community was evacuated for more than two weeks in spring due to the threat of an early-season wildfire.

B.C.’s heat alert and response system is the result of work by a committee struck in January 2022 to help the province respond to extreme heat events.

It followed the deadly heat-dome event of summer 2021, when temperatures soared above 40 C in many communities between June 25 and July 1.

The BC Coroners Service reported 619 heat-related deaths that summer.

Castellan said the current heat wave will be different because temperatures aren’t expected to surpass the heat-warning criteria by such large margins.

He said Wednesday that he expects Environment Canada will issue additional warnings as the heat moves from west to east across the province.

The agency says risks associated with heat are elevated for seniors and people with conditions such as diabetes, heart disease and mental health challenges.

The heat warnings encourage people to watch for signs of heat illness including heavy sweating, rashes, and fainting, and also to check in on friends and neighbours who may be at greater risk, especially if they live by themselves.

The BC Centre for Disease Control says heat waves are expected to “become more frequent, longer, and hotter” in the province due to climate change.