# HEADLINE
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HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING
# DETAILS
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WHAT
Heat index values up to 107.
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.
ISSUED AT
Tuesday, July 21, 2026 at 2:48 PM CDT
ISSUED BY
National Weather Service St Louis MO
HEADER
URGENT - WEATHER MESSAGE
# PRECAUTIONARY/PREPAREDNESS ACTIONS
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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.
# AREAS AFFECTED
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Madison MO, Monroe IL, Montgomery MO, Saint Louis MO, Washington MO, Boone MO, Callaway MO, Clinton IL, Cole MO, Crawford MO, Franklin MO, Gasconade MO, Iron MO, Jefferson MO, Madison IL, Moniteau MO, Osage MO, Randolph IL, Reynolds MO, Saint Charles MO, Saint Clair IL, Saint Francois MO, Saint Louis City MO, Sainte Genevieve MO, Warren MO, Washington IL
Including the cities of Fulton, Alton, Columbia, Edwardsville, Belleville, Saint Louis, Farmington, Cahokia, Sparta, Jefferson City, Union, Sullivan, Chester, Washington, and Saint Charles