textproduct: Central Illinois

KEY MESSAGES

- Typical summertime heat and humidity will prevail Tuesday through Saturday with heat index values peaking at or above 100 degrees each afternoon.

DISCUSSION

Issued at 119 PM CDT Mon Jul 13 2026

A Rex Block featuring a prominent upper-level ridge over the Upper Midwest and weak troughing over the Southern Plains into the Deep South will dominate the weather this week. This will lead to a prolonged period of hot summer weather with minimal rain chances. Temperatures will reach the upper 80s and lower 90s on Tuesday, then will hover in the lower to middle 90s Wednesday through Saturday. Given boundary layer moisture bolstered by peak evapotranspiration from maturing crops, dewpoints will climb into the lower to middle 70s...resulting in peak heat index readings of 100 degrees or higher each afternoon. While this level of heat is nothing out of the ordinary for mid-July in central Illinois, the NWS HeatRisk climbs into the moderate category Wednesday through Saturday. People who are particularly sensitive/vulnerable to heat such as the elderly and those with health issues should therefore take precautions.

Meanwhile further north, a series of short-wave troughs traversing central Canada will eventually phase and dig into Quebec/New England by the end of the week. This will gradually flatten the prevailing upper ridge and lead to a small increase in rain chances beginning as early as Thursday afternoon. As additional short-wave energy sharpens the NE trough, it will eventually push a cold front through central Illinois late Saturday into Sunday. After that, the synoptic models all strongly suggest a return to deep-layer NW flow across the Midwest and a resulting lowering in temperatures by early next week. The latest Climate Prediction Center (CPC) 8-14 day temperature outlook reflects the pattern change with a return to near normal temperatures from July 20-26.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 644 PM CDT Mon Jul 13 2026

VFR conditions will prevail at all TAF sites next 24hrs. Clear skies are expected through the night with light and variable winds. Scattered CU is expected to develop tomorrow with winds out of the east-northeast at 10kts or less.

ILX WATCHES/WARNINGS/ADVISORIES

None.