textproduct: Central Illinois

KEY MESSAGES

- Dry and seasonably cool weather this weekend will precede a bona fide warmup. Daily average temperatures from Monday to Thursday will be about 15 degrees warmer than what is considered normal for early January.

- Our next best chance (40-60%) for meaningful rain arrives Thursday.

DISCUSSION

Issued at 1210 PM CST Thu Jan 1 2026

Partial sunshine has returned this afternoon following the passage of a cold front to our south. High pressure will settle over the Upper Midwest and Great Lakes for the remainder of the weekend, resulting in seasonably cool temperatures. Two disturbances are expected to track across the central and southern Plains on Friday and Saturday. Although any associated precipitation will remain south of our forecast area, we anticipate an increase in high clouds, leading to filtered sunshine.

A significant warm-up is anticipated next week. This will be driven by strong low-level warm advection across the southern Plains, leading to mid-level height increases over the Midwest. Dry conditions are expected to continue, though we will need to monitor two brief periods - Sunday night and again on Tuesday for the potential of sprinkles as disturbances move across the Upper Mississippi Valley. Currently, the chance for rain during either period is less than 15% for our area. The presence of residual low- level dry air will likely prevent any meaningful precipitation; however, a slight, last-minute moistening within the broad warm advection pattern could support a light spritz.

Daily average temperatures from Monday to Thursday are expected to be about 15 degF warmer than what is considered normal for early January. Highs will reach the low-to-mid 50s, with overnight lows cooling to the low-to-mid 30s.

Our next meaningful chance for precipitation arrives Thursday as a robust mid-level shortwave trough tracks across Baja California. This disturbance's position is anticipated to draw in Pacific and Gulf moisture, increasing the probability of precipitation across parts of the Midwest. Current guidance, including the NBM and other ensembles, suggests a medium probability (40-60%) of precipitation, with the Mean QPF of 0.25 to 0.5". Temperatures will be warm with this system, and depending on the precise track and evolution of the disturbance, there is a possibility for strong thunderstorms.

MJA

AVIATION

(For the 00z TAFs through 00z Friday Evening) Issued at 549 PM CST Thu Jan 1 2026

A weak surface front is slowly lifting north this evening, bringing the return of scattered to broken low stratus to most of central Illinois. Confidence in how long the stratus sticks around is somewhat low, though conditions should improve no later than Friday morning as an area of high pressure approaches from the north. Winds remain light and variable through the overnight hours, becoming north-northeasterly by mid morning with speeds of 5-7 kts.

NMA

ILX WATCHES/WARNINGS/ADVISORIES

None.