Best AC Setting When It’s 110°F Outside

If it’s 110°F outside, we suggest setting your air conditioner around 75–78°F while you’re home, then adjusting it to a temperature where you can comfortably rest and sleep. You do not need to keep your house within 20 degrees of the outdoor temperature; a 110°F day does not mean your indoor target has to be 90°F.

If anyone in your household is older, very young, pregnant, has a medical condition, or takes medication that affects heat tolerance, prioritize a reliably cool room over an energy-saving target and follow any temperature guidance from their clinician. Our team also recommends checking the temperature in the rooms you actually use, since an upstairs bedroom or sun-facing room may be much warmer than the thermostat reading.

Close blinds on sunny windows, keep exterior doors shut, and use fans to help you feel cooler, but remember that a fan does not lower the room’s temperature. If you’ll be away, you can raise the thermostat a few degrees to save energy, provided the indoor conditions will remain safe for pets, plants, and anyone staying home; you can lower it again before bedtime if that helps you sleep.

If your air conditioner cannot keep up during a 110°F day, avoid heat-producing chores, drink water, and consider spending time in an air-conditioned public place rather than waiting in an increasingly hot home. Our guide to dressing for humid heat offers clothing ideas for hot weather, and our Stay Cool in Humid Heat – Summer Wardrobe Guide is a digital download for planning what to wear; neither replaces a safely cooled indoor space.