Heat Advisory issued September 18 at 2:58AM CDT until September 18 at 8:00PM CDT by NWS St Louis MO

**Heat Advisory issued September 18 at 2:58AM CDT until September 18 at 8:00PM CDT by NWS St Louis MO**

* WHAT...Heat index values up to 105.

* WHERE...In Illinois, Fayette IL, Montgomery IL, Calhoun IL, Greene IL, Jersey IL, and Macoupin IL Counties. In Missouri, Boone MO, Callaway MO, Lincoln MO, and Montgomery MO Counties.

* WHEN...Until 8 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat illnesses.

**What You Should Do:**

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.

**Alert Details:**

- **Severity:** Moderate

- **Urgency:** Expected

- **Issued by:** NWS St Louis MO

- **Effective:** Sep 18, 2026 2:58 AM UTC

- **Expires:** Sep 18, 2026 6:00 PM UTC

*This alert was automatically distributed from the National Weather Service via the IPAWS All-Hazards Information Feed.*