Heat Advisory

Locations Affected

Saint Louis, MO ∙ Columbia, MO ∙ O'Fallon, MO ∙ Saint Charles, MO ∙ Saint Peters, MO ∙ Florissant, MO ∙ Ladue, MO ∙ Green Park, MO ∙ Fredericktown, MO ∙ Riverview, MO

Full Alert Message

URGENT - WEATHER MESSAGE National Weather Service St Louis MO 248 AM CDT Tue Jul 21 2026 ...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING... * WHAT...Heat index values of 100 to 110 degrees. * WHERE...Portions of south central and southwest Illinois and central, east central, and southeast Missouri. * WHEN...Until 7 PM CDT this evening. * IMPACTS...Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS...This is the fourth straight day with heat index values of 100 degrees or higher over parts of the area. PRECAUTIONARY/PREPAREDNESS ACTIONS... Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1.

---