A persisting heat wave in the Pacific Northwest and western Canada continues to fuel hundreds of wildfires in three Canadian provinces and several states across America.

Smoke from the fires have drifted hundreds of miles away, causing a heavy gray haze to settle over the Pacific coast and turning sunsets a reddish-orange hue all the way to Washington, D.C.

Authorities issued air quality advisories across British Columbia on Monday as the unrelenting heat wave that began in early June sent temperatures soaring to record highs. More than 20 fires were sparked on Sunday alone, according to officials, AP reports.

The fires have caused the evacuation of more than 13,000 people in the sparsely populated Canadian province of Saskatchewan, making it the biggest wildfire evacuation there, according to CBC News.

"This is absolutely the biggest evacuation we've experienced in Saskatchewan," Red Cross spokeswoman Cindy Fuchs told reporters on Sunday, CBC reports. 

The total amount of personnel devoted to wildfire suppression in Saskatchewan alone is expected to top 1,500 this week as soldiers deploy to the La Ronge region, according to Mashable.

People with medical conditions, as well as the elderly and the very young, were urged to remain indoors and limit strenuous activity.

Local authorities have imposed a province-wide ban on open burning.