textproduct: Central Illinois

KEY MESSAGES

- A Frost Advisory is in effect tonight along and west of a Lacon...to Lincoln...to Taylorville line.

- Frost will be likely across all of central and southeast Illinois Saturday night as winds become nearly calm. Sensitive outdoor plants need to be protected this weekend in order to avoid damage.

DISCUSSION

Issued at 157 PM CDT Fri Oct 16 2026

18z/1pm surface analysis shows a 998mb low over southern Quebec with a cold front extending southward to the Gulf Coast. Meanwhile a sprawling 1046 high is building into the Plains. The pressure gradient between the departing front and the approaching high has resulted in strong/gusty northwesterly winds across central Illinois today. The latest regional observations continue to indicate gusts of 25-30mph and these will continue for the next few hours before gradually beginning to diminish toward sunset. Ample cloud cover blankets the region as a trough axis drops southward out of Wisconsin/Michigan. Once the trough sinks south of central Illinois, synoptic subsidence on its back side will allow skies to at least partially clear by mid to late evening...followed by clear skies across nearly the entire KILX CWA overnight. The exception will be along and east of a Danville to Casey line where a persistent lake-effect band will result in continued partly to mostly cloudy conditions through dawn Saturday. While skies will become clear elsewhere, winds will remain in the 10-15mph range through the evening. As the pressure gradient continues to loosen, winds will eventually drop below 10mph and may become light/variable across the Illinois River Valley toward daybreak. With lows dropping into the lower to middle 30s and overnight winds diminishing, have opted to continue the Frost Advisory for locations along/west of a Lacon...to Lincoln...to Taylorville line.

High pressure will build overhead on Saturday, resulting in sunny skies and light winds with chilly highs in the upper 50s to around 60 degrees. While winds will be calm Saturday evening, a light S/SE return flow will develop across the western half of the CWA overnight as the high slowly shifts eastward into the Ohio River Valley. With clear skies and very light winds, it appears Saturday night will feature a better shot at widespread frost across all of central and southeast Illinois. A Frost Advisory will likely be needed.

After that, the rest of the 7-day forecast looks quiet as upper ridging builds over the Midwest. While an occasional weak short-wave trough may temporarily impede the process and bring a few clouds and perhaps even a light shower, the overall pattern is decidedly warmer and drier. Highs will start out near seasonal normals in the middle to upper 60s on Sunday...then will approach 80 degrees by next Wednesday-Friday.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 622 PM CDT Fri Oct 16 2026

Widely scattered showers should come to an end over the next few hours. Skies will clear from west to east later tonight as high pressure works in, allowing winds to ease. VFR conditions are expected through Saturday with winds becoming light and variable.

ILX WATCHES/WARNINGS/ADVISORIES

Frost Advisory from 1 AM to 9 AM CDT Saturday for ILZ027>031- 036-037-040>042-047>052.