textproduct: Central Illinois

KEY MESSAGES

- Seasonable temperatures today are forecast to warm well above normal into mid week across central and southeast IL, and remain above normal through at least Saturday. There is a 40-80% chance (per NBM guidance) of temperatures reaching 65 degrees or warmer on Christmas Day along and southwest of a Macomb to Lincoln to Terre Haute line.

- There's a 20-50% chance of light showers in southeast IL Monday night. There is a 20-30% chance of light showers across much of the area Wednesday afternoon and Wed night along with some drizzle into early Thu morning. Rainfall amounts should stay less than a tenth inch if they occur.

DISCUSSION

Issued at 330 AM CST Sun Dec 21 2025

The 09Z/3 am surface analysis shows 1027-1029 mb Canadian high pressure over central Iowa and north central MO and ridging into sw/southern IL. NW winds 5-10 mph have brought in cooler subfreezing temperatures back into the area, with temps in the mid 20s to lower 30s, with lower 20s at Galesburg and Macomb. Band of mid/high clouds was southeast of a Danville to Taylorville line while a smaller band of mid/high clouds was streaming eastward across northern MO into west central IL. A semi-zonal mid/upper level flow prevailed across much of the country with an upper level trof near the Quebec/Ontario province line and into the Great Lakes region. A subtropical ridge (500 mb heights of 585-588 dm) was over Mexico and Baja of California.

High pressure is forecast to strengthen to 1030-1032 mb by midday as it drifts over IL then 1033-1035 mb during this evening as it settles eastward over the Ohio river valley. Mid/high clouds to decrease over southeast IL during this morning while mainly just some passing cirrus clouds over sw CWA today. So a fair amount of sunshine and lighter winds generally under 10 mph. Seasonable temperatures today with highs in the mid to upper 30s (coolest from I-74 ne) in central IL and lower 40s in southeast IL from I-70 south and over west central IL from Jacksonville west/sw. Mid/high clouds to increase later this evening and overnight especially northern CWA. Lows this evening of 22-28F (coolest east central IL) to slowly increase to around 30/lower 30s by daybreak Monday as SSE winds gradually increase.

Large high pressure will be over the mid Atlantic States Monday while weak low pressure moves eastward across northern Nebraska, lifting a warm front ne into northeast MO and sw IL by sunset Monday. A weak disturbance lifting up the lower MS river valley and into the lower Ohio river valley by Mon evening, to bring slight chance of light rain showers to se IL Mon afternoon and 20-50% chance of light showers to southeast IL Monday night from Danville to Effingham southeast. Rainfall amounts should stay under a tenth inch if they occur. Breezy southerly winds gusting 20-25 mph on Monday with milder highs in the mid to upper 40s, with southeast IL around 50F with a fair amount of low cloud cover spreading into CWA during Monday morning.

Isolated light showers could linger in far southeast IL early Tue morning, otherwise Tue is looking like a nice day with more sunshine and lighter winds expected along with warmer temperatures as strong mid/upper level ridge starts to build into the eastern plains and MS river valley Monday night/Tue. A weak cold front to push se through central IL Tue afternoon and into southeast IL Tue evening but should pass through dry with limited moisture and CAA. Highs Tue range from upper 40s/lower 50s northern CWA to upper 50s to around 60F in southeast IL. This will be the start of well above normal temperatures expected the rest of the week.

A warm front to lift back northeast over central IL Wed afternoon and evening and combined with a weak short wave ridging top of upper level ridge into central/northern IL Wed afternoon and Wed night to bring chance of light rain showers. More low clouds expected Wed into Thu morning and could see some drizzle too. Temps on Wed will be dependent on movement of warm front and likely late day highs with mid 50s from I-74 ne and 60-65F from Springfield to Paris south. Warm front should pass ne of IL by daybreak Thu with Christmas Day likely enjoying record warmth with highs in the 60s and even approaching 70F in southeast IL and sw of Springfield. Low pressure to pass north of area Thu night and bring a cold front southward into central IL overnight Thu night into Fri along with low chances of rain showers Thu night, with highest chances to our northeast. Some cooling Fri/Sat though models have trended a bit milder with latest runs as mid/upper level ridge holds longer over the area. Highs could still reach the 50s over much of area Fri/Sat, even lower 60s in southeast IL Friday. A deeper upper level trof and storm system to move into the eastern US next Sunday/Mon (Dec 28-29) and likely brings colder temperatures and possible chance of precipitation.

Climate Prediction Center (CPC) 6-10 Day Outlook for Dec 26-30th has a 70-80% chance of above normal temperatures over central/se IL and near normal precipitation. CPC 8-14 Day Outlook for Dec 28-Jan 3 continues trend of above normal temperatures (60-70%) with near normal precipitation central IL and 33-40% above normal precipitation in southern/southeast IL.

07

AVIATION

(For the 12z TAFs through 12z Monday Morning) Issued at 505 AM CST Sun Dec 21 2025

VFR conditions will prevail the next 24 hours, with mainly periods of high-based clouds. Winds will become light and variable this morning as high pressure drifts overhead, before becoming more southeasterly and increasing again by evening. Some potential for LLWS late in the TAF period near KPIA, though core of the jet looks to stay just west of there at this point.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.