St. Peters, Missouri Weather:
Active Weather Warnings
Thursday, August 13, 2026
Sunny with a Chance of Thunderstorms
Day 95°
Night 77°
Precipitation 55 %
Wind 8 mph
UV Index (0 - 11+) 8
Weather Forecast History
Last Year's Weather on This Day (August 13, 2025)

Day

90°

Night

70°

Weather Alerts and Warnings for

Severe Expected Likely

Extreme Heat Warning

Extreme Heat Warning issued August 12 at 1:45AM CDT until August 13 at 8:00PM CDT by NWS St Louis MO
Aug 12, 1:45 AM Aug 13, 8:00 PM
WHAT: Dangerously hot conditions with heat index values up to 111.

WHERE: Portions of south central and southwest Illinois and
central and east central Missouri.

WHEN: Until 8 PM CDT Thursday.

IMPACTS: Heat related illnesses increase significantly during
extreme heat and high humidity events.
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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. People in the Saint Louis Metropolitan Area can get information about cooling centers or energy assistance related to the excessive heat by calling the United Way of Greater Saint Louis at 800-427-4626, or if calling from a land line phone dial 2-1-1. You can also call Cool Down Saint Louis at 314-241-7668.
Updated: Aug 12, 6:45 AM Source: NWS Alert