textproduct: Central Illinois

KEY MESSAGES

- Dangerous heat continues across central Illinois through early evening, with peak heat index values ranging from 100 to 110F.

- A cold front brings welcomed relief Sunday and Monday, pushing high temperatures into the 80s for most locations and dropping heat indices into the 80s and 90s.

- High heat and humidity return Tuesday and Wednesday, bringing another risk for triple-digit heat index values.

LONG TERM

(Tuesday through Friday) Relief will be short-lived as the strong upper-level ridge is progged to expand back eastward into the Midwest by Tuesday and Wednesday. This will trigger a resurgence of widespread 90-degree temperatures, with triple-digit heat index values once again possible.

By mid-week, a closed upper-level low over the Pacific Northwest will open and advance east across the Canadian Prairies, buckling the upper ridge. In response, a surface low will deepen as it lifts across Manitoba on Tuesday and toward Hudson Bay on Wednesday. The trailing cold front will sag southward into the Upper Midwest, with its southern tail / col area eventually pushing into central Illinois on Wednesday. Precipitation chances with this frontal passage remain quite low (10-20%) due to weak convergence and the displacement of the primary upper-level support far to the north.

Chances for more substantial rainfall increase (40-50%) Thursday night into Friday morning. This is in response to a strengthening low-level jet to our west, which will drive renewed thunderstorm development along the stalling frontal boundary.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 602 PM CDT Sat Sep 5 2026

North-northeast winds will continue to veer to the east through Sunday morning behind a backdoor cold front. A period of patchy low stratus is possible into early Sunday morning, but confidence in this occurring remains low (<30% chance). Otherwise, VFR conditions are expected through the TAF period.

CLIMATE

Issued at 1215 AM CDT Sat Sep 5 2026

Record high temperatures for Saturday:

Location Sat 9/5 ======== ======== Bloomington 103/1899 Champaign 102/1899 Charleston 102/1954 Danville 102/1954 Decatur 104/1954 Jacksonville 104/1899 Lincoln 103/1954 Olney 106/1925 Paris 105/1954 Peoria 104/1899 Springfield 99/1954

ILX WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 7 PM CDT this evening for ILZ027>031-036>038-040>057-061>063-066>068-071>073.