Rising temperatures pose new challenges for firefighters who have made incremental progress against a massive wildfire in central California that has injured four people as it has become the biggest blaze in the state so far this year.

More than 800 structures are being threatened by a massive wildfire burning through Los Padres National Forest in central California

Air quality has taken a serious hit across the United States as a twofold blow of wildfires in the West and in Canada have sent smoke pouring across large sections of the country — a problem that’s set to linger for days.

A thin veil of smoke from wildfires burning in Canada is worsening air quality and putting a lid on temperatures in the D.C. area. The smoke, which has resulted in some of the world’s worst air quality in the Upper Midwest and Northeast, is only wafting through the Mid-Atlantic in limited quantities, but it’s enough to have a small impact.