textproduct: Central Illinois

KEY MESSAGES

- Light winds, clear skies, and temperatures dropping into the mid 30s at daybreak, will result in frost development over much of central and southeast IL early this morning. A Frost Advisory is in effect through 8 AM this morning across central and southeast IL. Take precautions for sensitive vegetation.

- Temperatures dropping into the low to mid 30s overnight, will result in more widespread frost development. HREF has a 60-80% chance of temperatures getting to 32F or colder northeast of a Rushville to Decatur to Terre Haute line by dawn Monday. The Freeze Watch has been upgraded to a Freeze Warning from Fulton to Logan to Edgar counties north from 1-8 am Monday, with a Frost Advisory south (not including Clay, Richland and Lawrence counties). Take precautions for sensitive vegetation by covering with cloth or taking indoors. - Seasonably cool temperatures early this week, will rebound into the mid to upper 70s Tuesday and Wednesday, and lower 80s Thursday. A stronger storm system will likely bring showers and thunderstorms to the area Thursday night through Friday evening with NBM having 40-70% potential of 1 inch or more of rain possible.

DISCUSSION

Issued at 345 AM CDT Sun Apr 19 2026

Continued the Frost Advisory until 8 am this morning over CWA as temps settle into the mid to upper 30s by sunrise, with Galesburg getting near freezing (GBG currently 34F at 330 am).

The 08Z/3 am surface analysis shows 1027 mb high pressure over southeast Oklahoma and and ridging into the upper Ohio river valley providing clear skies and light SW winds over central/se IL. The 3 am temperatures were in the mid 30s to around 40F over the area. A cold front was over central WI and southern MN into southeast SD. The cold front is forecast to track southward into northern CWA during midday, and near highway 50 in southeast IL by sunset. Scattered to broken mid level clouds over MN and northern Iowa should move southward across CWA with the cold front during late morning and afternoon. Moisture and lift is limited with this front and should mostly pass through dry though a few sprinkles may be possible this afternoon. West to SW winds to switch nw behind the cold front this afternoon and gusts 25-35 mph from the IL river southeast. HREF has a 50-80% chance of surface wind gusts over 30 mph from IL river se this afternoon. Highs today in the mid to upper 50s from I-74 north and lower 60s from Lincoln to Paris south.

1025 mb Canadian high pressure along the southern Saskatchewan and Manitoba province line to settle into southern Lake MI by sunrise Monday and strengthen to 1030 mb. This to return clear skies to central/se IL during tonight along with winds diminishing light by overnight as they veer north to NE. Temps will be a few degrees colder tonight in the low to mid 30s. HREF has a 60-80% chance of temperatures getting to 32F or colder northeast of a Rushville to Decatur to Terre Haute line by dawn Monday. So the Freeze Watch has been upgraded to a Freeze Warning from Fulton, Logan and Edgar counties north from 1-8 am Monday, with a Frost Advisory south, though not including far southern 3 counties of Clay, Richland and Lawrence.

High pressure shifts into the mid Atlantic States and New England by dawn Tue while a warm front lifts ne into central IL. A fair amount of sunshine Monday with lighter winds becoming south 5-10 mph Mon afternoon. Highs Monday in the upper 50s and lower 60s with mid 60s from Jacksonville sw toward the MS river valley. Not as cold Monday night with southerly flow, with lows in the mid to upper 40s, coolest near the IN border. Breezy sw winds gusting 25-30 mph by Tue afternoon brings milder highs in the mid to upper 70s with partly to mostly sunny skies.

A weak cold front slips down into the southern Great Lakes Tue night and could bring low chances of showers and isolated thunderstorms to central IL. The front appears to stay north and ne of CWA Tue night and Wed, with upper level ridge building over the MS river valley and IL on Wed. Pretty nice day expected Wed with sw winds 5-15 mph and partly to mostly sunny skies with highs in the mid to upper 70s again. Even warmer on Thu with highs 80-85F with breezy southerly winds gusting to 30 mph by Thu afternoon.

A stronger storm system off the northern California Coast to eject into the upper Midwest Thu night with an associated strong surface low pressure 990 mb or stronger passing nw of MN by dawn Fri. Approaching cold front during Thu night to increase chances of showers and thunderstorms from west to east especially by overnight Thu night and continue Friday as cold front moves through. Another disturbance passing south of IL on Sat could keep chances of showers around on Saturday especially southeast IL. ECMWF and GEM models have qpf over southern 2/3rds of CWA Sat while GFS keeps qpf just south of CWA. Drier conditions look more likely across area by next Sunday. Seasonable temps expected next weekend with highs in the mid to upper 60s Sat/Sun with se IL near 70F.

The Climate Prediction Center (CPC) 8-14 Day Outlook for Apr 26-May 2 has around a 40-50% chance of below normal temperatures across IL. CPC has a 33-40% chance of above normal precipitation over central IL, while areas north of Peoria are trending near normal for precipitation.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1223 AM CDT Sun Apr 19 2026

A weak trough will dig across the region Sunday afternoon. Ahead of the trough, a modest WSW/W breeze will be in place with gusts to around 20 kt developing mid morning. Winds will veer to the northwest behind the trough with gusts picking up more into the mid 20kt range. High pressure will spread across the upper Midwest Sunday evening causing winds to veer out of the N to NE Sunday evening and drop back below 10 kt. VFR conditions are expected through the period.

ILX WATCHES/WARNINGS/ADVISORIES

Frost Advisory until 8 AM CDT this morning for ILZ027>031- 036>038-040>057-061>063-066>068-071>073. Freeze Warning from 1 AM to 8 AM CDT Monday for ILZ027>031- 036>038-041>046-055-057. Frost Advisory from 1 AM to 8 AM CDT Monday for ILZ040-047>054- 056-061>063-066>068.