Stay prepared for extreme heat

Read the local warning

Heat warnings reflect local criteria and expected impacts. Humidity, overnight temperatures, direct sunshine and the length of a hot spell can all matter. The temperature on a city forecast is modeled for a location and does not measure conditions inside a parked vehicle or every building.

Reduce exposure

Plan strenuous outdoor activities for cooler periods, take breaks in a cool place and keep water available. Check on people who may need help reaching a cooler location. Never leave children or pets in parked vehicles. Follow local health and emergency-service advice, including any instructions tailored to you.

Plan beyond the afternoon high

A warm night can make it harder to cool a building. Review both the daytime highs and nighttime lows in the forecast, and know where you can go if your usual cooling is unavailable. If someone appears seriously unwell during heat, contact emergency services promptly.

Use the forecast fields that matter at night

A single afternoon high does not describe the risk. Look at the overnight low and the length of the hot spell. Buildings that do not cool down keep people at risk after the sun sets. Humidity and direct sun are not fully captured by one temperature number. The city value is a model estimate for a point, not the temperature inside a parked car, a top-floor apartment or a worksite in the sun.

Who needs a cooler place arranged in advance

Older adults, infants, people who work outside and anyone who cannot easily increase fluids or reach air-conditioning are the groups public-health guidance asks you to check on. Identify a library, mall or cooling center before a heat warning is issued. Never leave a child, an older person or a pet in a parked vehicle. If someone is confused, faint or stops sweating in extreme heat, contact emergency services. This guide is not medical advice for a specific person.

Sources and further reading

Official National Weather Service reference. Source checked September 28, 2026. This general guide does not replace a current warning or advice from local authorities.