Residents across much of southern Alberta, central and southeast Saskatchewan and British Columbia's southern Interior are sweltering through a hot spell.
Environment Canada heat warnings or special weather statements are posted in those regions.
The Fraser Canyon community of Lytton, B.C., which often claims the title of hottest place in the country, is forecast to reach a high of 40 C, while the city of Kamloops is expected to be just one degree cooler.
Temperatures are lower in Alberta and Saskatchewan, but high humidity in many areas, including Lethbridge, Medicine Hat and Saskatoon, will make it feel close to 40 C.
The weather office says Saskatchewan should cool by Friday, but the hot weather is forecast to continue through the weekend in B.C. and Alberta.
Heat in B.C. follows an unseasonably wet June and July, but now residents are being warned to take care in the backcountry because conditions have dried considerably.
The current wildfire danger is rated as high to extreme across the southern quarter of the province and Forests Minister Doug Donaldson says fire safety must be top of mind.
"Fighting wildfires can be challenging at the best of times, but managing them in the midst of the COVID-19 pandemic requires BC Wildfire Service staff to operate with even greater care," he says in a statement.
The wildfire service responded to 239 fires in B.C. between the start of the wildfire season on April 1 and July 29.
Human activity is blamed for sparking about 85 per cent of those blazes.