textproduct: Central Illinois

KEY MESSAGES

- Well above normal temperatures are forecast from Tuesday through Saturday with highs in the 50s and 60s. Highs in the 60s will be common over much of central and southeast IL on Thursday and Friday, and approaching 70F on Christmas Day along and southwest of a Quincy to Springfield to Terre Haute line.

- There's a 20-50% chance of light showers in southeast IL tonight along with patchy fog and drizzle overnight into early Tue morning. More chances of light rain showers, patchy fog and drizzle at times to occur over central IL Wednesday into Thursday night and be most common from I-74 northeast.

DISCUSSION

Issued at 330 AM CST Mon Dec 22 2025

The 09Z/3 am surface analysis shows 1035 mb high pressure over the eastern Ohio river valley (WV and Southeast Ohio) and ridging into the mid MS river valley. A weak disturbance over the upper MS river valley was bringing mid level clouds as far south as a Quincy to Springfield to Terre Haute line while mostly clear skies south with some cirrus clouds. Light mixed precipitation should stay well north of CWA over southern MN into central WI this morning. Radar mosaic shows virga over northern IL, just north of CWA early this morning. Subfreezing temperatures at 3 am were in the upper 20s/lower 30s over CWA with SE winds 5-15 mph.

Large high pressure to push east near the mid Atlantic Coast by sunset while low pressure system over the northern Rockies emerges over western Nebraska and near KS/CO border with its warm front extending into sw parts of Iowa and IL and northeast MO. Low clouds lifting northward into southeast KS and sw MO from LA/AR and eastern parts of Texas and OK. These low clouds should lift into west central IL during mid morning, as far east at highway 51 during lunch time and to the IL/IN border during mid afternoon. So will see increasing low clouds during today with breezy SSE winds gusting 17-25 mph. Highs today in the mid to upper 40s in central IL (coolest northern CWA) and lower 50s in southeast IL.

A weak disturbance lifting ne from lower MS valley into the lower Ohio river valley tonight, to bring isolated light rain showers to areas from Flora to Terre Haute se late this afternoon, and then 20-50% chance of showers from Danville to Effingham se tonight. Added patchy fog and drizzle to southeast IL tonight and early Tue morning as low stratus clouds around 1k ft get into east central/se IL. The HRRR model even shows a period of dense fog possible overnight in east central and southeast IL. Milder lows tonight in the upper 30s/lower 40s central IL and mid 40s in southeast IL.

1028-1030 mb Canadian high pressure to settle se into the upper Midwest/upper MS river valley by sunset Tue and into the central Great Lakes region by dawn Wed. This will push a weak cold front SSE through central IL late Tue afternoon and Tue evening, and should pass through quietly with limited lift along it. Should see skies become partly to mostly sunny during Tue afternoon before clouds increase again during Tue night. Highs Tue range from lower 50s northern CWA form Macomb to Bloomington north, to the lower 60s in southeast IL south of I-70.

Models have trended slower with frontal boundary lifting back northward across central IL during Wed, now appearing to lift into sw CWA and southeast IL during Wed afternoon and over rest of CWA during Wed evening. Low clouds/stratus with some fog and drizzle likely north of the warm front Wed and Wed night. Plus a weak disturbance riding top of mid/upper level ridge will be near central IL Wed night and giving chance of light rain showers too especially ne CWA. Highs Wed will be tricky depending how far warm front gets. We have cooler highs Wed in the lower 50s from I-74 north and lower 60s from Keokuk, Iowa to Springfield to Terre Haute south where warm front appears to get through during Wed afternoon. Warm front should be in northern IL on Christmas Day with our area seeing unseasonably warm 60s, with lower 60s from I-74 north and upper 60s to around 70F from Macomb to Springfield to Terre Haute south. Record highs in the 60s will be in jeopardy of being tied or broken especially south of I-74. A stronger disturbance tracks ESE over the Great Lakes and northern Ohio river valley Thu night and could bring chance of showers to especially ne CWA with better chance of rain closer to the Great Lakes.

Models show cold front pushing back se over IL on Fri, with Ecmwf and GEM models slower than the GFS model. Blend of models going with the slower route which would mean warmer highs for central and se IL Friday especially se of the IL river where 60s appear likely again, with upper 60s to near 70F along and southeast of I-70. Frontal boundary appears to hang up in central MO and southern IL Sat keeping above normal temps in the area. Highs Sat 55-60F in central IL and 60-65F in southeast IL.

Deepening upper level trof into the Midwest and Great Lakes Sat night and Sunday to push a stronger cold front se through IL during Sat night, and bringing chance of showers Sat night along with much colder air for Sunday and Monday as temps cool closer to seasonable levels. Highs in the upper 30s/lower 40s Sunday and Monday (mid 40s southeast of I-70 on Sunday).

The Climate Prediction Center (CPC) 6-10 Day Outlook for Dec 27-31 has a 70-75% chance of above normal temperatures over central and southeast IL with precipitation trending near or slightly above normal. CPC 8-14 Day Outlook for Dec 29-Jan 4 has a 60-70% chance of above normal temperatures over CWA with a 33-40% chance of above normal precipitation.

07

AVIATION

(For the 12z TAFs through 12z Tuesday Morning) Issued at 504 AM CST Mon Dec 22 2025

VFR conditions prevailing at present, but an area of ceilings lowering to around 4000 feet is expected to spread into central Illinois this afternoon. A tongue of even lower clouds will track northeast out of southern Illinois this evening, mainly impacting areas around KCMI/KDEC, where HREF probabilities of ceilings below 2000 feet increase to around 60%. Toward the end of the TAF period, IFR conditions spread over eastern Illinois and may impact these sites as well.

LLWS threat lingers for a couple hours this morning at KPIA/KSPI, as regional Doppler radar wind profiles show about a 35 knot low level jet from southern Wisconsin into central Missouri. At the surface, south/southeast winds gradually become more southwest by 06Z, generally around 10 knots or so.

Geelhart

ILX WATCHES/WARNINGS/ADVISORIES

None.