A sustained heatwave began in British Columbia on Sunday and is expected to last for most of the coming week, as provincial authorities warned residents to prepare for the potential impact of the prolonged period of oppressive temperatures.

Environment Canada’s heat warnings covered much of British Columbia’s southern coast on Sunday, with more expected to take effect inland and beyond on Monday.

Temperatures are expected to top 30 degrees Celsius in some areas, prompting Disaster Relief Minister Bowinn Ma to urge residents to avoid the heat, drink water and limit outdoor activities.

The ministry released a statement on Saturday, saying the heatwave predicted for this week is not expected to be as severe as the 2021 heatwave, which reported 619 deaths, but warned residents about possible health effects from prolonged heat exposure should be prepared.

“Most at risk are the elderly, particularly those living alone, and those with health conditions such as mental illness, substance use disorders, physical disabilities, cognitive impairment, respiratory disease, heart disease, kidney disease and diabetes, the ministry statement said. Pregnant women, infants and young children are also at increased risk.

The pools of water are drying up

Forestry Secretary Bruce Ralston said above-average temperatures would quickly dry up watersheds and people should continue to conserve water.

More than 80% of the province has reached drought level 4 or 5, the highest possible rating.

Seventeen of British Columbia’s 34 watersheds are experiencing Stage 4 drought conditions, meaning damage to ecosystems and communities is likely. Eleven other pools are at Level 5, meaning every effort should be made to conserve water and protect critical environmental flows.

Environment Canada is forecasting temperatures of up to 38C in Kamloops on Wednesday, while temperatures in Port Alberni will remain around 30C throughout the week.

The agency issued heat warnings along the south coast on Saturday. It forecasts temperatures in Vancouver, the Fraser Valley and Howe Sound will soar to 33C between Sunday and Wednesday, with overnight lows of around 17C. Temperatures are expected to drop a few degrees on Thursday.

Meanwhile, in eastern Vancouver Island and the Sunshine Coast, daytime temperatures of between 29 and 32C are expected through Wednesday, with overnight lows of around 16C.

Environment Canada issued another warning for the South Thompson and Southern Fraser Canyon areas on Sunday, saying the heatwave in those areas will begin on Sunday. The agency expects daytime temperatures of up to 38°C and overnight lows of 18°C.

“Daytime temperatures well above seasonal normals and high overnight lows offer little relief from the heat,” the heat warning said.

Separate heat warnings are in place for Kootenay Lake, where temperatures are expected to reach 37C between Monday and Thursday, and North Thompson, where highs of 29C are expected.

“A strong ridge of high pressure will push temperatures up the south coast,” Environment Canada said, noting that the heatwave in those regions will begin Monday.

Special weather bulletins were also issued in the southern Okanagan areas, including Penticton, and northern Cariboo between Monday and Thursday. The weather agency said Friday will see seasonal temperatures return.

Cooler nighttime temperatures in those areas will provide some heat relief, but Environment Canada said a heat warning would be issued if nighttime temperatures reach 18C or more in the South Okanagan and if they rise above 14C in the northern Cariboo region.