Nearly 900 wildfires continued to burn across Canada on Monday, as military assistance arrived in British Columbia and plumes of smoke triggered air quality warnings in more than a dozen U.S. states. The blazes have doubled in number since mid-June, and several provinces and territories have recently set new record-high temperatures, causing experts to worry that the hot and dry conditions will accelerate the burning. In B.C., there were 373 active wildfires on Monday, with 110 considered out of control, according to Sarah Budd, an information officer with the BC Wildfire Service. Of those, 23 were considered fires of note, meaning they were highly visible or had the potential to impact people, communities or critical infrastructure. Ms. Budd said forests in the province’s northern half have sustained repeated lightning strikes over the past 15 days, which have fed the flames.