textproduct: Central Illinois

KEY MESSAGES

- Dry fuels and low relative humidity will lead to an elevated risk for afternoon agricultural field fires today through Saturday, especially southeast of the IL river.

- There is a slight chance for showers and thunderstorms Friday morning from I-74 north. Rainfall amounts should be light.

- The next widespread chance for rain is late Saturday into Sunday, especially over east central and southeast IL. Latest LREF has a 40 to 60 percent chance for more than a half inch of rain southeast of a Paris to Effingham line. A 20 percent chance over half inch rain as far northwest as Taylorville to Urbana. LREF has a 20 percent chance of 1 inch or more of rain from Lawrenceville southeast.

DISCUSSION

Issued at 355 AM CDT Thu Oct 8 2026

The 08Z/3 am surface map shows 1020 mb high pressure over central ND and ridging se into Iowa and near the IL/MO border. A cold front that pushed southward through IL yesterday was well south of IL near the TN river valley. Nearly clear skies over central and southeast IL with few high clouds nw of the IL river and no fog observed yet over CWA. Temps were in the upper 40s/lower 50s in central IL with mid 50s over Clay, Richland and Lawrence counties.

A delightful day ahead weatherize for central/se IL as weak high pressure settles over IL by midday and drifts lower MI and upper Ohio river valley by dawn Fri. Ample sunshine again today with a few passing high/cirrus clouds with light winds under 10 mph due to nearby surface high pressure ridge. Highs in the upper 70s northern CWA and lower 80s central and southern CWA with areas south of I-70 approaching 85F. Lows tonight in the low to mid 50s, coolest in eastern IL with some upper 40s possible near the IN border. Increasing clouds tonight mainly overnight over central IL with fair skies in southeast IL.

Showers and isolated thunderstorms likely develop overnight over Iowa with WAA from SW 850 mb jet of 25-35 kts and some increase in moisture. Elevated instability with forecast MUCAPE of 500-1000 J/kg to move into areas nw of the IL river Friday morning supporting isolated thunderstorms there along with 20-40% chance of showers. Isolated to scattered convective. activity from Peoria/I-74 north Friday morning, gradually shifts ne of CWA early Friday afternoon as low level jet weakens with skies becoming mostly sunny Friday afternoon as 500 mb ridge builds northward into IL. Warm highs Friday in the low to mid 80s, with upper 80s from Springfield and Effingham sw.

Upper level ridging into IL Fri night and Saturday and should keep much of CWA dry thru sunset Sat, though we will see clouds increasing from the south during the day Saturday and we have a slight chance of showers late Sat afternoon from highway 50 south due remnants of Hurricane Isaias approaching from the south. Milder lows Fri night in the upper 50s/lower 60s and warm highs in the low to mid 80s Sat, coolest southeast of I-70 where clouds move in quicker on Saturday.

Hurricane Isaias become 1st hurricane of this season in the Atlantic basin with 75 mph at 1 am and nw of the Yucatan peninsula. The National Hurricane Center (NHC) forecast Isaias to track ne and then turn northward and intensify further to 100-110 mph as it reaches near the far western tip of FL near AL gulf coast border late Fri evening, then weaken it it lifts northward over western TN Sat evening. This tropical system to spread deeper tropical moisture northward into the mid MS and Ohio river valley late Sat afternoon into Sunday, with rain likely moving over east central and se IL during Sat night and Sunday morning, and diminishing during Sunday afternoon. We have slight chance of thunderstorms in southeast IL from late Sat evening into Sunday morning. Brunt of rain chances appear to be from I-55 east. Latest LREF has a 40 to 60 percent chance for more than a half inch of rain southeast of a Paris to Effingham line. A 20 percent chance over half inch rain as far northwest as Taylorville to Urbana. LREF has a 20 percent chance of 1 inch or more of rain from Lawrenceville southeast. More clouds and rain showers around keeps cooler highs in the lower 70s in eastern IL east of I-57 on Sunday with upper 70s over the IL river valley where drier conditions expected.

Remnants of Isaias moves out quickly into the upper Ohio valley and central Appalachians during Sunday night with strong mid/upper level ridging building into IL Sunday night and Monday. Warm again on Monday with highs in the 80s (upper 80s to near 90F from Springfield sw). A deepening low pressure system moving into southeast Canada Monday night and Tue to push a cold front se through CWA overnight Mon night into Tue morning. Forcing and moisture is limited with this front this far sw and mainly have slight chances of showers over northern/eastern CWA Mon night into Tue with light rainfall amounts if they happen at all. Highs Tue in the low to mid 70s central IL and upper 70s in southeast IL. Weak high pressure settles into the upper Midwest Tue and Tue night with upper level ridging into IL Tue night into Wed. Deepening upper level trof/low over the Rockies during middle of next week to eject a stronger storm system ne into the Midwest around Wed night/Thu time frame of next week bringing our next showers of showers and possible thunderstorms along with cooler temperatures later next week into 2nd weekend of October.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 550 AM CDT Thu Oct 8 2026

High pressure over eastern ND and ridging se over Iowa and into west central IL at dawn, to settle over IL by midday and to shift into the eastern Ohio river valley overnight. Nearby high pressure ridge will maintain VFR conditions over central IL airports through 12Z/7 am Fri along with light winds. Winds generally NW direction today and trending east to SE overnight. Few to scattered cirrus clouds prevail today with scattered to broken mid to high clouds spreading in from the west/nw late evening/overnight. WAA driven isolated to scattered convection developing over parts of Iowa overnight should stay nw of central IL airports thru 12Z/7 am Fri. But isolated convection could affect northern terminals (PIA/BMI) during Fri morning after this TAF cycle.

ILX WATCHES/WARNINGS/ADVISORIES

None.