textproduct: Central Illinois

KEY MESSAGES

- Intermittent chances for showers and thunderstorms resume Wednesday and continue through the weekend, though the majority of the time will likely be dry.

- After a cool start to the work week, temperatures will moderate to generally near average by the middle-end of the week and then above normal for the second part of the weekend and into the beginning of next week.

DISCUSSION

Issued at 328 AM CDT Tue Jun 23 2026

One more dry day as high pressure slowly drifts across the area and into Indiana. Once the high pressure is east of the area, the northwest flow will bring the next weather system into the area Wed. The associated low pressure area will remain well north in the northern Miss valley while a frontal boundary extends south into the plains. As this front moves into the area Wed, mid 60 dewpoints will advect northward back into the area creating an unstable environment. This will result in showers and storms developing over the area and moving east, mainly tomorrow night. Some models show scattered light rain over the area Wed morning, but pops will be low enough to not warranted a mention at this time. The time period with the greatest pops will be Wed night in the northeast. As is typical this time of year, the front is forecasted to remain over the area the rest of the week and into the weekend. Showers and storms are expected from Wed night through Sat; however, at this time, severe weather is not expected. This could change as models come into better agreement over the next couple of days.

Rainfall amounts will be quite hefty from Wed night through Fri night, with 2+ inches currently being forecasted for parts of central and southeast IL. These amounts will likely be from heavy thunderstorms due to the high PW values of 1.75 inches or higher through the period. Given the stationary nature of the boundary as well, training of thunderstorms over the same area could lead to flash flooding and the likely return of rising rivers, mainly south of I-72/Danville. Plus the ground is already moist from heavy rainfall from the last 3-5 days. A flood watch will not be issued at this time, but may be needed in later forecasts.

A break in the precip should occur after the main wave pushes east into the eastern US on Sunday. As this occurs, high pressure ridge will quickly build into the Miss valley and dry weather is currently expected to finish out the month of June...Sunday through Tue.

Cooler temps in the 70s will continue one more day, but then a warming trend will occur. With a stationary boundary near by for mid week to end of the week, temps will warm some, but clouds and precip could keep that in check. Temps around 80 are expected through end of the week, with mid 80s returning Sat. However, with a building ridge for last part of the weekend and into the beginning of next week, a quick transition to summer is expected with temps reaching into the 90s for Sun through Tue.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1247 PM CDT Tue Jun 23 2026

VFR conditions will prevail through the entire 18z TAF period. FEW-SCT diurnal Cu at 4000-5000ft will develop east of the Illinois River this afternoon...with perhaps a few periods of BKN Cu along/west of the river. Once these clouds fade away prior to sunset, a high/thin overcast will be observed early this evening before NAM/HRRR forecast soundings indicate a BKN-OVC mid-level deck at around 12,000ft will spread across the area overnight into Wednesday morning. A few showers/thunderstorms may develop along/west of I-55 in advance of a cold front toward midday Wednesday, but opted to leave precip mention out of the TAFs until model/radar trends dictate. Winds will initially be light/variable, then will become S/SW at 8-12kt by Wednesday morning.

ILX WATCHES/WARNINGS/ADVISORIES

None.