textproduct: Central Illinois

KEY MESSAGES

- Temperatures will average 10 to 15 degrees above seasonal normals through most of next week, with only modest cooling toward late week.

- Tranquil weather will continue for several more days, with the only meaningful chance of rain toward the middle of next week.

DISCUSSION

Issued at 112 PM CDT Fri Oct 23 2026

Omega block pattern remains in place over the CONUS late this week, with an upper level high pressure ridge across the central U.S. bookended by lows over southwest Montana and off the Canadian Maritimes. Some flattening/leaning of the ridge will take place this weekend as low pressure moves across the Canadian prairies, but the only real consequence for our area will be some higher level clouds at times. Temperatures will continue a large diurnal spread, from mid-upper 40s at night to mid- upper 70s during the day. Most high temperature records across the region should be just out of reach, but a few may be approached over west central Illinois.

As we get into the work week, the ridge will very gradually slide off to the east, with little change in temperatures. It will take until mid week before we finally see some change in the pattern. Tuesday morning, synoptic models are in good agreement with a broad trough over the Pacific Northwest, pushing toward the northern Plains on Wednesday. At that point, the guidance begins to differ. The GFS solution becomes slower/weaker as a low develops over southwest British Columbia, which would result in lighter rain chances toward Thursday and a rebuilding of the ridge late in the week. The European solution deepens a trough over central parts of Canada/U.S. and a quick shot of showers Wednesday night, slowly moving the trough through the Great Lakes late week.

Temperatures become more uncertain late in the week, with NBM box-and-whiskers plots showing temperature spreads of 15 to 20 degrees in the 25-75th percentiles (both highs and lows). While the European ensembles do trend toward below normal temperatures late next week, a non-trivial number retain above normal tendencies into the Halloween weekend. GFS ensembles are more solidly in the warmer trend, as would be expected with ridging overhead.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1200 PM CDT Fri Oct 23 2026

VFR conditions to continue through Saturday, with only scattered high-level clouds at times. South/southeast winds will average 5-7 knots through the period.

ILX WATCHES/WARNINGS/ADVISORIES

None.