World leaders may face smoke warnings when they gather next week in Alberta as wildfires burned out of control across much of Canada and caused the country's second-worst fire season in decades. The Kananaskis area of the Canadian Rocky Mountains,

Forecasters warn that hazy, grayish-blue skies could persist for many weeks as fires continue to burn, though most smoke will remain high in the atmosphere.

More than 200 wildfires are blazing across Canada, forcing 27,000 people to evacuate and creating hazardous air quality all over the U.S.