textproduct: Central Illinois

KEY MESSAGES

- Frost will be likely across areas generally east of I-55 tonight. Sensitive outdoor plants need to be protected this weekend in order to avoid damage. A Frost Advisory is in effect tonight near and east of a Bloomington...to Decatur...to Taylorville line.

- Temperatures will begin a warming trend. Highs tomorrow will be in the mid 60s, but by midweek temperatures will be back well above normal with highs in the upper 70s, nearing 80.

DISCUSSION

Issued at 220 PM CDT Sat Oct 17 2026

High pressure is set up over the central part of the United States. This will bring clear skies and dry weather to IL for the next several days to a week. Winds have also become very light to near calm. The main focus of this forecast is the temperatures and the frost potential tonight. Temperatures will drop down into the mid 30s tonight. With clear skies, light winds, and cold temperatures frost formation is favorable in eastern IL, focused east of I-55 tonight. If radiational cooling overperform, temperatures could get near freezing in some spots. There is a Frost Advisory in effect for that area from 1am to 9am tomorrow morning. There could be some very localized, patchy frost that develops in west-central IL in the lowest/coolest spots.

Temperatures will begin a warming trend tomorrow. Highs tomorrow will be in the mid 60s, but by midweek temperatures will be back well above normal with highs in the upper 70s, nearing 80. Normals for this time of year is around 65-69 degrees across central and southeastern IL.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 607 PM CDT Sat Oct 17 2026

VFR conditions are expected through the TAF period. Winds will be light and variable overnight, increasing out of the south by mid morning.

ILX WATCHES/WARNINGS/ADVISORIES

Frost Advisory from 1 AM to 9 AM CDT Sunday for ILZ038-043>046- 052>057-061>063-066>068-071>073.