FPUS53 KLSX 181518 ZFPLSX Zone Forecasts National Weather Service Saint Louis MO 1018 AM CDT Sat Jul 18 2026 ILZ100-101-MOZ061-063-064-182300- Madison IL-Saint Clair IL-Saint Charles MO-Saint Louis MO- Saint Louis City MO- Including the cities of Alton, Edwardsville, Belleville, Cahokia, Saint Charles, and Saint Louis 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds around 10 mph. Heat index values up to 103. .TONIGHT...Partly cloudy. A slight chance of showers and thunderstorms after midnight. Humid with lows in the mid 70s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 102 early in the evening. .SUNDAY...Mostly sunny. A chance of showers and thunderstorms in the afternoon. Humid with highs around 90. Northeast winds around 5 mph. Chance of rain 50 percent. Heat index values up to 102. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Sunny with highs in the lower 90s. South winds around 5 mph. Heat index values up to 106. .MONDAY NIGHT AND TUESDAY...Mostly clear. Lows in the upper 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the mid 80s. Heat index values up to 100. .WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. .THURSDAY...Mostly sunny. Highs in the lower 80s. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the mid 60s. Highs in the mid 80s. $$ MOZ049-050-182300- Osage MO-Callaway MO- Including the city of Fulton 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. West winds 5 to 10 mph with gusts up to 20 mph. Chance of rain 20 percent. Heat index values up to 100. .TONIGHT...Mostly clear in the evening, then becoming partly cloudy. Humid with lows in the lower 70s. West winds 5 to 10 mph. .SUNDAY...Mostly sunny. Showers likely with a chance of thunderstorms in the afternoon. Humid with highs in the lower 90s. West winds around 5 mph, becoming north in the afternoon. Chance of rain 60 percent. Heat index values up to 101. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Sunny with highs in the lower 90s. Southwest winds around 5 mph. Heat index values up to 104. .MONDAY NIGHT AND TUESDAY...Mostly clear. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. Highs in the mid 80s. .THURSDAY...Mostly sunny with a 20 percent chance of showers. Highs in the lower 80s. .THURSDAY NIGHT...Mostly cloudy in the evening, then partly cloudy with a chance of showers after midnight. Lows in the mid 60s. Chance of rain 30 percent. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ MOZ042-182300- Audrain MO- Including the city of Mexico 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. West winds around 10 mph with gusts up to 20 mph. Chance of rain 20 percent. .TONIGHT...Partly cloudy. A slight chance of showers and thunderstorms after midnight. Lows in the lower 70s. West winds 5 to 10 mph. Chance of rain 20 percent. .SUNDAY...Mostly sunny. A chance of showersand thunderstorms in the afternoon. Humid with highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 50 percent. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Lows around 70. Southeast winds around 5 mph. Chance of rain 30 percent. .MONDAY...Sunny with highs in the lower 90s. Southwest winds 5 to 10 mph. Heat index values up to 101. .MONDAY NIGHT AND TUESDAY...Mostly clear. Lows in the mid 70s. Highs in the lower 90s. Heat index values up to 100. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. Highs in the lower 80s. .THURSDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the upper 70s. Chance of rain 20 percent. .THURSDAY NIGHT...Mostly cloudy in the evening, then partly cloudy with a chance of showers after midnight. Lows in the mid 60s. Chance of rain 30 percent. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the lower 80s. Chance of rain 20 percent. $$ MOZ041-047-048-182300- Boone MO-Moniteau MO-Cole MO- Including the cities of Columbia and Jefferson City 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. West winds 5 to 10 mph with gusts up to 20 mph. Chance of rain 20 percent. Heat index values up to 100. .TONIGHT...Mostly clear. Humid with lows in the mid 70s. West winds 5 to 10 mph. .SUNDAY...Mostly sunny. A chance of showers and thunderstorms in the afternoon. Humid with highs in the lower 90s. Light and variable winds, becoming north around 5 mph in the afternoon. Chance of rain 50 percent. Heat index values up to 103. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the mid 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 30 percent. .MONDAY...Sunny, hot with highs in the mid 90s. Southwest winds around 5 mph. Heat index values up to 105. .MONDAY NIGHT AND TUESDAY...Mostly clear. Hot. Lows in the upper 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the upper 60s. Highs in the upper 80s. .THURSDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the lower 80s. Chance of rain 20 percent. .THURSDAY NIGHT...Mostly cloudy in the evening, then partly cloudy with a chance of showers after midnight. Lows in the upper 60s. Chance of rain 30 percent. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the upper 80s. Chance of rain 20 percent. $$ ILZ095>097-MOZ018-019-026-027-034>036-182300- Adams IL-Brown IL-Pike IL-Knox MO-Lewis MO-Shelby MO-Marion MO- Monroe MO-Ralls MO-Pike MO- Including the cities of Quincy, Mount Sterling, Pittsfield, Hannibal, and Bowling Green 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. West winds 5 to 10 mph with gusts up to 20 mph. Chance of rain 20 percent. Heat index values up to 102. .TONIGHT...Partly cloudy with a slight chance of showers and thunderstorms. Humid with lows in the lower 70s. West winds 5 to 10 mph, becoming northwest after midnight. Chance of rain 20 percent. Heat index values up to 100 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 20 percent. .SUNDAY NIGHT...Partly cloudy. Lows around 70. East winds around 5 mph. .MONDAY...Sunny with highs in the lower 90s. South winds around 5 mph. Heat index values up to 104. .MONDAY NIGHT...Mostly clear. A slight chance of showers and thunderstorms after midnight. Lows in the mid 70s. Chance of rain 20 percent. Heat index values up to 105 early in the evening. .TUESDAY AND TUESDAY NIGHT...Mostly clear. Highs in the lower 90s. Lows in the mid 60s. .WEDNESDAY AND WEDNESDAY NIGHT...Mostly clear. Highs in the mid 80s. Lows in the lower 60s. .THURSDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the lower 80s. Chance of rain 20 percent. .THURSDAY NIGHT...Partly cloudy. A slight chance of showers in the evening, then a chance of showers after midnight. Lows in the mid 60s. Chance of rain 40 percent. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ ILZ069-074-182300- Clinton IL-Washington IL- 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds 5 to 10 mph. Heat index values up to 104. .TONIGHT...Partly cloudy. A slight chance of showers and thunderstorms after midnight. Humid with lows in the mid 70s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 103 early in the evening. .SUNDAY...Mostly sunny. A chance of showers and thunderstorms in the afternoon. Humid with highs in the upper 80s. North winds around 5 mph. Chance of rain 50 percent. Heat index values up to 101. .SUNDAY NIGHT...Partly cloudy. Lows around 70. Northeast winds around 5 mph in the evening, becoming light and variable. .MONDAY...Mostly sunny. Humid with highs in the lower 90s. Light and variable winds. Heat index values up to 106 in the afternoon. .MONDAY NIGHT...Mostly clear in the evening, then becoming partly cloudy. Lows in the mid 70s. Heat index values up to 105 early in the evening. .TUESDAY...Sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. Chance of rain 20 percent. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the lower 80s. Heat index values up to 100. .WEDNESDAY NIGHT AND THURSDAY...Partly cloudy. Lows in the lower 60s. Highs in the lower 80s. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the mid 60s. Highs in the lower 80s. $$ ILZ070-182300- Marion IL- Including the cities of Centralia and Salem 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds around 10 mph. Heat index values up to 103. .TONIGHT...Partly cloudy with a slight chance of showers and thunderstorms. Humid with lows in the lower 70s. West winds 5 to 10 mph in the evening, becoming light and variable. Chance of rain 20 percent. Heat index values up to 101 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Humid with highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 20 percent. .SUNDAY NIGHT...Mostly clear in the evening, then becoming partly cloudy. Lows in the upper 60s. East winds around 5 mph in the evening, becoming light and variable. .MONDAY...Mostly sunny. A slight chance of showers in the morning. Humid with highs in the lower 90s. Light and variable winds. Chance of rain 20 percent. Heat index values up to 101. .MONDAY NIGHT...Mostly clear in the evening, then becoming partly cloudy. Lows in the mid 70s. .TUESDAY...Sunny. A slight chance of showers and thunderstorms in the morning, then a chance of showers and thunderstorms in the afternoon. Highs in the lower 90s. Chance of rain 30 percent. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the lower 80s. .WEDNESDAY NIGHT...Mostly clear. Lows in the lower 60s. .THURSDAY...Mostly sunny. Highs around 80. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in themid 60s. Highs in the lower 80s. $$ MOZ074-084-085-099-182300- Saint Francois MO-Iron MO-Madison MO-Reynolds MO- Including the city of Farmington 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Sunny late this morning, then becoming partly sunny. A slight chance of showers and thunderstorms this afternoon. Highs in the lower 90s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 100. .TONIGHT...Partly cloudy with a slight chance of showers and thunderstorms in the evening, then mostly clear after midnight. Lows in the lower 70s. West winds around 5 mph in the evening, becoming light and variable. Chance of rain 20 percent. .SUNDAY...Mostly sunny. Showers likely with a chance of thunderstorms in the afternoon. Humid with highs around 90. Northwest winds around 5 mph. Chance of rain 70 percent. Heat index values up to 102. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. Light and variable winds. Chance of rain 40 percent. .MONDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Humid with highs in the lower 90s. Light and variable winds, becoming southwest around 5 mph in the afternoon. Chance of rain 20 percent. Heat index values up to 103. .MONDAY NIGHT AND TUESDAY...Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the mid 80s. Heat index values up to 100. .WEDNESDAY NIGHT...Mostly clear. Lows in the lower 60s. .THURSDAY AND THURSDAY NIGHT...Partly cloudy. Highs in the lower 80s. Lows in the mid 60s. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ MOZ051-060-182300- Montgomery MO-Warren MO- 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. West winds 5 to 10 mph with gusts up to 20 mph. Chance of rain 20 percent. Heat index values up to 101. .TONIGHT...Mostly clear in the evening, then partly cloudy with a slight chance of showers and thunderstorms after midnight. Humid with lows in the lower 70s. West winds 5 to 10 mph. Chance of rain 20 percent. .SUNDAY...Mostly sunny. Showers likely with a chance of thunderstorms in the afternoon. Humid with highs around 90. Light and variable winds, becoming northeast around 5 mph in the afternoon. Chance of rain 60 percent. Heat index values up to 102. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows around 70. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Sunny with highs in the lower 90s. Light and variable winds, becoming southwest around 5 mph in the afternoon. Heat index values up to 104. .MONDAY NIGHT AND TUESDAY...Mostly clear. Lows in the mid 70s. Highs in the lower 90s. Heat index values up to 105. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. Highs in the mid 80s. .THURSDAY...Mostly sunny. Highs around 80. .THURSDAY NIGHT...Mostly cloudy in the evening, then partly cloudy with a chance of showers after midnight. Lows in the lower 60s. Chance of rain 30 percent. .FRIDAY...Mostly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ MOZ052-182300- Lincoln MO- 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds 5 to 10 mph with gusts up to 20 mph. Heat index values up to 102. .TONIGHT...Mostly clear in the evening, then partly cloudy with a slight chance of showers and thunderstorms after midnight. Humid with lows in the lower 70s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 100 early in the evening. .SUNDAY...Mostly sunny. Showers likely with a chance of thunderstorms in the afternoon. Humid with highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 60 percent. Heat index values up to 101. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Sunny with highs in the lower 90s. South winds around 5 mph. Heat index values up to 105. .MONDAY NIGHT AND TUESDAY...Mostly clear. Lows in the mid 70s. Highs in the lower 90s. Heat index values up to 105. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. Highs in the mid 80s. .THURSDAY...Mostly sunny. Highs in the lower 80s. .THURSDAY NIGHT...Partly cloudy. A chance of showers after midnight. Lows in the mid 60s. Chance of rain 30 percent. .FRIDAY...Partly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ ILZ058-059-098-099-182300- Greene IL-Macoupin IL-Calhoun IL-Jersey IL- 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds around 10 mph with gusts up to 20 mph. Heat index values up to 101. .TONIGHT...Partly cloudy with a slight chance of showers and thunderstorms. Humid with lows in the lower 70s. West winds 5 to 10 mph, becoming northwest after midnight. Chance of rain 20 percent. Heat index values up to 100 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Humid with highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 20 percent. .SUNDAY NIGHT...Partly cloudy. Lows in the upper 60s. East winds around 5 mph. .MONDAY...Sunny with highs in the lower 90s. South winds around 5 mph. Heat index values up to 102. .MONDAY NIGHT...Mostly clear in the evening, then partly cloudy with a slight chance of showers and thunderstorms after midnight. Lows in the mid 70s. Chance of rain 20 percent. Heat index values up to 100 early in the evening. .TUESDAY AND TUESDAY NIGHT...Mostly clear. Highs in the lower 90s. Lows in the mid 60s. Heat index values up to 100. .WEDNESDAY AND WEDNESDAY NIGHT...Mostly clear. Highs in the lower 80s. Lows in the lower 60s. .THURSDAY...Mostly sunny. Highs in the lower 80s. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the lower 60s. Highs in the mid 80s. $$ ILZ060-064-065-182300- Montgomery IL-Bond IL-Fayette IL- Including the cities of Litchfield and Vandalia 1018 AM CDT Sat Jul 18 2026 .REST OF TODAY...Mostly sunny. Highs around 90. West winds around 10 mph. Heat index values up to 101. .TONIGHT...Partly cloudy. A chance of showers and thunderstorms, mainly in the evening. Humid with lows in the lower 70s. West winds 5 to 10 mph, becoming north after midnight. Chance of rain 30 percent. Heat index values up to 100 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Highs in the upper 80s. Northeast winds around 5 mph. Chance of rain 20 percent. .SUNDAY NIGHT...Partly cloudy. Lows in the upper 60s. East winds around 5 mph in the evening, becoming light and variable. .MONDAY...Sunny with highs around 90. South winds around 5 mph. Heat index values up to 102. .MONDAY NIGHT...Mostly clear in the evening, then partly cloudy with a chance of showers and thunderstorms after midnight. Lows in the mid 70s. Chance of rain 40 percent. Heat index values up to 100 early in the evening. .TUESDAY...Sunny with a slight chance of showers and thunderstorms. Highs in the lower 90s. Chance of rain 20 percent. Heat index values up to 100. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the mid 60s. Highs in the lower 80s. .WEDNESDAY NIGHT...Mostly clear. Lows around 60. .THURSDAY...Mostly sunny. Highs around 80. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the lower 60s. Highs in the lower 80s. $$ ILZ079-MOZ075-182300- Randolph IL-Sainte Genevieve MO- Including the cities of Chester and Sparta 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny. A slight chance of showers and thunderstorms this afternoon. Highs in the lower 90s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 102. .TONIGHT...Partly cloudy. Humid with lows in the lower 70s. West winds around 5 mph. Heat index values up to 101 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the morning, then showers likely with a chance of thunderstorms in the afternoon. Humid with highs around 90. Northwest winds around 5 mph. Chance of rain 70 percent. Heat index values up to 104. .SUNDAY NIGHT...Mostly cloudy with a chance of showers and thunderstorms in the evening, then partly cloudy after midnight. Humid with lows in the lower 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Mostly sunny. A slight chance of showers and thunderstorms in the afternoon. Humid with highs in the lower 90s. Light and variable winds, becoming southwest around 5 mph in the afternoon. Chance of rain 20 percent. Heat index values up to 107 in the afternoon. .MONDAY NIGHT AND TUESDAY...Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the mid 80s. Heat index values up to 105. .WEDNESDAY NIGHT AND THURSDAY...Partly cloudy. Lows in the lower 60s. Highs in the lower 80s. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the mid 60s. Highs in the lower 80s. $$ MOZ059-062-072-073-182300- Gasconade MO-Franklin MO-Crawford MO-Washington MO- Including the cities of Washington, Union, and Sullivan 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny. A slight chance of showers and thunderstorms this afternoon. Highs in the lower 90s. West winds 5 to 10 mph. Chance of rain 20 percent. Heat index values up to 100. .TONIGHT...Partly cloudy. Lows in the lower 70s. West winds around 5 mph. .SUNDAY...Mostly sunny. Showers likely with a chance of thunderstorms in the afternoon. Humid with highs around 90. Northwest winds around 5 mph. Chance of rain 70 percent. Heat index values up to 103. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. Light and variable winds. Chance of rain 40 percent. .MONDAY...Sunny. A slight chance of showers and thunderstorms in the afternoon. Humid with highs in the lower 90s. Light and variable winds, becoming southwest around 5 mph in the afternoon. Chance of rain 20 percent. Heat index values up to 104. .MONDAY NIGHT AND TUESDAY...Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...Mostly clear. Lows in the mid 60s. Highs in the mid 80s. .THURSDAY AND THURSDAY NIGHT...Partly cloudy. A 20 percent chance of showers. Highs in the lower 80s. Lows in the mid 60s. .FRIDAY...Partly sunny. A slight chance of showers in the morning. Highs in the mid 80s. Chance of rain 20 percent. $$ ILZ102-MOZ065-182300- Monroe IL-Jefferson MO- 1018 AM CDT Sat Jul 18 2026 ...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT TUESDAY... .REST OF TODAY...Mostly sunny. Highs in the lower 90s. West winds 5 to 10 mph. Heat index values up to 103. .TONIGHT...Partly cloudy. A slight chance of showers and thunderstorms after midnight. Humid with lows in the lower 70s. West winds around 5 mph. Chance of rain 20 percent. Heat index values up to 100 early in the evening. .SUNDAY...Mostly sunny. A slight chance of showers and thunderstorms in the morning, then showers likely with a chance of thunderstorms in the afternoon. Humid with highs around 90. Northwest winds around 5 mph, becoming north in the afternoon. Chance of rain 70 percent. Heat index values up to 105. .SUNDAY NIGHT...Partly cloudy. A chance of showers and thunderstorms in the evening. Humid with lows in the lower 70s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 40 percent. .MONDAY...Sunny with highs in the lower 90s. Light and variable winds, becoming southwest around 5 mph in the afternoon. Heat index values up to 107. .MONDAY NIGHT AND TUESDAY...Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105. .TUESDAY NIGHT AND WEDNESDAY...Mostly clear. Lows in the upper 60s. Highs in the mid 80s. Heat index values up to 100. .WEDNESDAY NIGHT...Mostly clear. Lows in the lower 60s. .THURSDAY...Mostly sunny. Highs in the lower 80s. .THURSDAY NIGHT AND FRIDAY...Partly cloudy. A 20 percent chance of showers. Lows in the mid 60s. Highs in the mid 80s. $$