textproduct: Central Illinois

KEY MESSAGES

- Dangerous heat and humidity will continue this afternoon, particularly near and south of Interstate 70 where there is a 40% to 60% chance that temperatures will exceed 90F. Heat index values in this southern corridor are expected to peak between 100F and 105F.

- Widespread thunderstorms are expected to develop this afternoon and evening across central Illinois (60-80% chance). While organized severe weather is unlikely, any storm could produce localized torrential rainfall leading to minor flooding, as well as isolated damaging wind gusts.

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

..Next Week

By midday Sunday, the primary upper-level shortwave trough axis will begin crossing the region, dragging an attendant surface cold front through central Illinois. Because airmass recovery occurs readily this time of year, boundary layer conditions ahead of the front appear favorable enough to support another round of scattered thunderstorms on Sunday afternoon.

The passage of this cold front will effectively scour out the multi-day tropical airmass. Dewpoints are forecast to drop back into the much more comfortable mid-60s to lower 70s by Monday.

A welcome stretch of seasonable and dry weather is anticipated from Monday through Wednesday as a transient shortwave ridge builds across the Midwest. Expect daytime highs to hover comfortably in the mid-80s during this period.

The midweek respite looks to be short-lived. Long-range guidance hints at a return to unsettled weather by late next week as a well- defined trough is projected to dig across the Upper Midwest. This system will drag another cold front into the region, which is modeled to stall somewhere over the state. This setup will reintroduce daily chances for showers and thunderstorms heading into the weekend.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1209 AM CDT Sat Jul 4 2026

Showers and thunderstorms are ongoing across central Illinois and are expected to continue overnight, though we should gradually see a diminishing trend in coverage. Storms are expected to redevelop over the region by Saturday afternoon and evening, though confidence in specifics (timing/location) is low at this time. Wind fields will be disrupted by convection in the region, thus expect quite a bit of variability in wind direction, though wind speed should generally stay under 10 kt outside of storms.

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.