textproduct: Central Illinois

KEY MESSAGES

- Dangerous heat and humidity over central and southeast IL this afternoon, particularly near and south of I-72 will improve as a line of thunderstorms tracks eastward across central IL during mid afternoon into early evening. Heat index values are expected to peak between 97 and 105 degrees this afternoon before the rains, with the highest values south of I-72.

- Scattered strong to severe thunderstorms will track eastward across central IL through early evening. There is a slight chance of severe storms mainly along and east of the IL river, with damaging winds the primary severe weather threat along hail and localized torrential rainfall of 1-3 inches that could lead to minor flooding especially in urban areas.

- A break from the heat wave arrives early next week. Following a final round of scattered showers and thunderstorms on Sunday, a cold front will bring a stretch of dry and comfortable weather with highs in the 80s from Monday through Wednesday.

Next Work Week

Isolated showers and thunderstorms are possible in east central and southeast IL Monday afternoon with weak upper level low/trof over the southern Great Lakes. Otherwise a welcome stretch of seasonable and generally dry weather is anticipated from Monday through Wednesday with weak surface high pressure settling into the Great Lakes region and upper level ridging back into IL Tue/Wed (500 mb heights rise to 588-590 decameters). Expect daytime highs to be in the low to mid 80s Monday and mid to upper 80s Tue and Wed.

The medium to long range forecast models show a more unsettled weather pattern returning to IL during the 2nd half of the week as an upper level trof moves into the area. A cold front to push into northern and possibly central IL around Friday and stall near the area into next weekend. his setup will reintroduce daily chances for showers and thunderstorms from Thursday into next weekend. The CIPS and CSU-MLP show marginal risk of severe storms over nw parts of CWA overnight Wed night, over more of CWA on Thu and southern/se CWA on Friday.

The Climate Prediction Center (CPC) 8-14 Day Outlook for July 12-18 has 33-40% chance of above normal temperatures and 33-40% of below normal precipitation over IL. CPC's Week 3-4 Outlook for July 18-31 shows equal chances of above or below normal temperatures and precipitation.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1245 PM CDT Sat Jul 4 2026

Expect scattered to broken bands of convection to develop and spread eastward across central IL during this afternoon. A few isolated thunderstorms have developed in past hour west of I-57 and tracking slowly ENE at 15 mph. We carried tempo groups for around 3 hours for MVFR conditions for thunderstorms and could see wind gusts over 40 kts with stronger storms. Brunt of convection to pass se of central IL airports after 23-24Z with isolated convection possible for a few hours until dusk. HRRR is showing MVFR ceilings and possible vsbys with fog developing overnight after 06-08Z especially along I-74. If these MVFR conditions develop, expected them to lift to VFR between 14-15Z Sunday morning. SW winds of 5-10 kts early this afternoon to switch west to NW later this afternoon and evening, and veer more northerly during tonight into Sunday morning.

ILX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 7 PM CDT this evening for ILZ029-031- 036>038-040>057-061>063-066>068-071>073.