Gridley, IL Weather

This Hazardous Weather Outlook is for central Illinois, east central Illinois, southeast Illinois and west central Illinois.

Day one

Tonight.

No hazardous weather is expected at this time.

Days two through seven

Saturday through Thursday.

No hazardous weather is expected at this time.

Spotter information statement

Spotter activation is not anticipated through tonight.

Key messages

- Light to moderate showers will track across central Illinois this afternoon through Sunday, bringing beneficial rainfall with little to no flooding impacts. Localized amounts of 0.50 to 0.75 inches remain possible northwest of the Illinois River today, but the chance of exceeding an inch over the weekend is under 10% areawide.

- Daily rain chances and mild temps with highs in the upper 60s and 70s continue into the first half of next week, with a 60% chance for rainfall to exceed one inch west of I-57 by Wednesday night.

- A cold front will pass through the region Wednesday night into Thursday, bringing blustery north winds and dropping daytime temperatures back into the 50s and possibly 40s in spots.

Discussion

Issued at 128 PM CDT Fri Oct 30 2026

NEAR TERM /THROUGH TONIGHT/: This afternoon, a broad surface high stretches from the Canadian Prairies into the Great Lakes. Isentropic ascent and mid-level warm air advection west of the ridge axis will drive showers and a few storms with the initial focus across northern Missouri into Iowa and west central Illinois early this afternoon, but spreading east across portions of central and east central Illinois through the remainder of the day. Weak elevated instability rooted near 800 mb will support shallow convection; however, poor mid-level lapse rates will keep equilibrium levels near or below the ice-growth zone, suppressing lightning potential. HREF LPMM shows the potential for localized rainfall swaths of 0.50 to 1.00 inch, especially northwest of the Illinois River Valley, but rainfall amounts will taper quickly further east with little to no measurable precip expected east of I-55.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/: Broad isentropic ascent across the 300-315K surfaces will further expand east across the Mississippi Valley over the weekend, bringing additional rain showers Saturday and Sunday. Weak mid-level lapse rates (<6.0 C/km) will continue to limit thunderstorm activity, but moisture transport will push precipitable water (PWAT) values up to 1.00-1.30 inches by Sunday afternoon--exceeding the 90th percentile of GEFS model climatology. NBM 48-hour mean QPF values average around 0.10 to 0.25 inches through Sunday night. NBM 90th percentile has trended down but still suggests isolated pockets exceeding 0.5-0.75 inches will be possible over the weekend. NBM probability for exceeding an inch is now less than 10% across the forecast area for the weekend. Given the antecedent dry conditions, any rainfall will be beneficial with negligible impacts.

LONG TERM /MONDAY THROUGH FRIDAY/: A closed upper-level low over the West Coast this weekend will dig southeastward across the Intermountain West Sunday night into the Central and Southern Plains Monday, inducing surface cyclogenesis over Colorado and Kansas. The upper low is projected to stall and slowly meander eastward across the mid/lower Mississippi Valley through midweek, ejecting several lobes of vorticity ahead of this feature and supporting daily chances for showers and a few storms through at least the first half of next week. NBM probabilities for reaching at least an inch of rain in 48-hours peak around 60% west of I-57 Wednesday evening/night. Mild temperatures in the upper 60s and 70s will dominate early to midweek.

Timing differences between the models persist but are starting to hone in on the surface low and attendant cold front passing through central Illinois Wednesday night into Thursday. High temperatures drop into the 40s and 50s in the wake of the system under a period of blustery northerly winds. Given the continued timing discrepancies among models, the NBM currently broad- brushes the thermal gradient late in the week averaging out the forecast highs in the 60s.

Aviation

Issued at 1208 PM CDT Fri Oct 30 2026

A stationary front is expected to remain just south of the terminals with a modest easterly breeze and isolated to scattered showers across central Illinois. VFR conditions should prevail through the period, but cannot rule out brief MVFR ceilings or vsby in or around showers. The thunder threat is low, but non-zero. As we head into the evening and overnight hours, the focus for precip is expected to shift slightly northward favoring PIA/BMI.

Watches, warnings and advisories

None.