Should you open your windows today?

Fresh air is free air conditioning — when conditions cooperate. The catch is that several things have to cooperate at once: outdoor temperature in a comfortable band, humidity that won't turn the house muggy, and air that's actually clean enough to invite inside.

This tool checks all of it for your city — current temperature and the day's trend, humidity, wind, and the live air quality index, which matters more than ever during wildfire season — and gives you a straight answer, including the hours of the day that look best.

The classic move in hot weather is timing: open up during the cool morning and evening hours, close up before the afternoon heat arrives, and let the house coast on the cool air you banked.