Keeping Your Home Cool on 100°F Days in the Valley

Help the AC

Keep the filter clean, the outdoor coil clear of dust and plants, and vents open and unblocked. A system that breathes freely copes with heat far better than one fighting a clogged filter or dirty coil.

Block the sun

Close blinds and curtains on west and south windows before the afternoon sun hits. Exterior shades and trees block even more heat before it reaches the glass.

Pre-cool

Cool the house a few degrees more in the morning, then let it drift up a little in the late afternoon. On time-of-use rates this can lower costs too.

Don't crank it down

Setting the thermostat very low won't cool faster and can freeze the coil. Pick a steady, comfortable setting.

Limit indoor heat

Avoid using the oven and dryer in the afternoon, and switch to LED bulbs, which give off less heat.

Check on people

Heat is dangerous for older adults, young children and anyone with health conditions. Know where local cooling centres are.

If the AC fails

Move to the coolest room, use fans, drink water and get help early rather than waiting for the hottest part of the day.

Get help

See AC repair.

Night air

On nights when it drops well below indoor temperature, opening windows briefly and running a whole-house or window fan can flush heat out of the house. Close up again before the sun gets high and smoke or pollen levels rise.

Attic heat

An attic baking at very high temperatures pushes heat down through the ceiling. Good insulation and attic ventilation keep upstairs rooms more comfortable and reduce the load on the AC.

More AC guides

• AC Won't Cool? What to Check First
• Replacing a Swamp Cooler With Central Air
• Wildfire Smoke and Your HVAC Filter
• Title 24 and Duct Testing: What Modesto Homeowners Should Know
• Hiring a Licensed HVAC Contractor in California