St. Louis heat advisory (July 18–21): cooling centers and what to do

A Heat Advisory is in effect for the St. Louis area starting noon Saturday, July 18, 2026 and lasting until 7:00 p.m. Tuesday, July 21, 2026 (CDT), with heat index values expected around 100 to 105.

The City of St. Louis is urging residents to take practical steps to reduce heat illness risk—especially for children, older adults, people with medical conditions, and anyone working outdoors.

How long the Heat Advisory lasts (and what to expect)

The National Weather Service’s Heat Advisory is scheduled to run from July 18 at 12:00 p.m. CDT through July 21 at 7:00 p.m. CDT. The City’s event notice says heat index values of 100 to 105 are expected.

Where to cool down: City cooling sites

If you need a place to cool off, the City maintains a Cooling Sites in the St. Louis Area list.

During periods of extreme heat, the City says it will declare a heat emergency and open community centers as cooling sites.

Because hours can change for holidays or summer weather events such as thunderstorms and rain, the City asks residents to verify before going—using 2-1-1 (or the regional 211 list) for the most up-to-date information.

What to do during the advisory

• Limit outdoor activity. Cut back on time in direct sun and avoid the hottest parts of the day when possible.
• Drink plenty of fluids. Don’t rely on thirst alone.
• Never leave people (or pets) in parked cars. The City’s hot-weather guidance says not even for a few minutes.
• Check on neighbors. The City’s cooling-sites guidance urges residents to check on older adults and other people who may be more vulnerable.

Heat illness quick guide: heatstroke is an emergency

The City’s “Hot Weather” page emphasizes that the most serious heat-related conditions are heatstroke and heat exhaustion.

Heatstroke basics: Heatstroke happens when the body can’t control its temperature. The City notes body temperature may rise to 106°F or higher within 10 to 15 minutes, and it can cause death or permanent disability without emergency treatment.

Heatstroke symptoms the City lists include: extremely high body temperature (above 103°F orally), red, hot and dry skin, rapid pulse, throbbing headache, dizziness, nausea, confusion, and unconsciousness.

If you suspect heatstroke: Move the person to a cool place—preferably an air-conditioned indoor setting. Outside, move to shade. Put the person in a semi-sitting position, loosen clothing, and bathe the head and body with COLD water. Seek medical attention immediately.

Need help cooling down or finding shelter?

• Heat alerts: Sign up for NotifySTL emergency alerts or download the Everbridge app.
• Air-conditioning installation or utility help: The St. Louis Fire Department will help seniors and individuals with disabilities install window air-conditioning units if they need assistance. Call 314-533-3406. Utility or air conditioner assistance is also available through Cool Down St. Louis at 314-241-0001.
• Shelter/outreach contacts: Shelter beds and outreach may be extended during extreme weather. The City lists the St. Louis Housing Helpline at (314) 802-5444 and says to call 2-1-1 for United Way resources.

With the advisory running through Tuesday evening, the takeaway is simple: plan ahead for a cool place, hydrate, and treat suspected heatstroke as urgent.

Sources

• National Weather Service (NWS) – Heat Advisory (St. Louis, MO point forecast)
• City of St. Louis Emergency Management – Hot Weather safety guidance