textproduct: Central Illinois

This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.

KEY MESSAGES

- Today/Tonight: Seasonably cool and mostly dry today. Low rain chances (20% or less) south of a Macomb-to-Effingham line today, expanding slightly overnight into Saturday morning along the I-70 corridor (up to 40% chance for thunderstorms).

- Weekend Heat Ramp-Up: Hotter air and oppressive humidity return rapidly over the weekend. Heat index values peak between 100-110F on Sunday and Monday, with heat headlines likely needed.

- Severe Weather Potential: A low-probability/high-impact severe weather threat lurks Sunday into Monday along the periphery of the ridge ("Ring of Fire" / Northwest flow setup), with Monday presenting the most favorable convective window ahead of an approaching cold front.

TUESDAY THROUGH THURSDAY

The cold front is forecast to sink slowly southward through the region on Tuesday. This frontal passage will gradually flush out the oppressive near-80F dewpoints, though lingering heat/humidity will persist across southeast Illinois through Tuesday afternoon (where dewpoints may hold in the 70s until late in the day). Afternoon highs Tuesday will remain warm in the upper 80s to near 90F.

From mid-to-late next week, central Illinois settles into a northwesterly flow pattern on the eastern edge of the central US ridge. While extreme buoyancy and high shear will subside relative to early-week levels, northwest flow regimes notoriously foster periodic MCS development upstream that can track through the region. For now, temperature and humidity levels look to return closer to early-August seasonable norms, with highs in the upper 80s and peak heat indices generally in the mid-90s.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 517 AM CDT Fri Jul 24 2026

Clouds will increase in coverage, gradually lowering throughout this TAF period. Model guidance is in excellent agreement that VFR conditions will dominate, but that the probability of MVFR ceilings increases to 50-70% beyond 09z.

Confidence and coverage of rain showers today remains too low to mention in this TAF cycle, but did add a PROB30 group for TSRA at KSPI and KDEC after 10z when coverage appears to expand.

Otherwise, surface winds will remain light and from the south.

ILX WATCHES/WARNINGS/ADVISORIES

None.

IMPORTANT This is an independent project and has no affiliation with the National Weather Service or any other agency. Do not rely on this website for emergency or critical information: please visit weather.gov for the most accurate and up-to-date information available.

textproduct.us is built and maintained by Joshua Thayer.