Millions from the Great Lakes to the Northeast are under air quality alerts – with the toxic smoke prompting a ground delay at Boston's Logan airport.

Smoke from a wildfire in San Luis Obispo and Santa Barbara counties is affecting air quality to start the week in Los Angeles. The Gifford Fire was estimated Monday morning at more than 65,000 acres. The fire started Friday in Los Padres National Forest. Containment was at 3 percent.

Tuesday night is when the high pressure system shifts to the east, the NWS says. This should allow south winds to return, which should usher out the smoke. But then it will bring on more heat and humidity. So get ready to turn your AC back on.