South Jacksonville, IL Weather

Key Messages

- Continued above-normal warmth and dry conditions are expected through Friday, with afternoon temperatures in the 70s to near 80 degrees solidifying one of the warmest Octobers on record.

- Scattered, light showers have a low chance (10% to 30%) Thursday, primarily near and north of Interstate 74, offering no significant relief to ongoing dry conditions.

- A pattern shift is favored by next weekend and early November, bringing higher confidence in cooler, breezier, and wetter weather.

Discussion

Issued at 1233 PM CDT Sun Oct 25 2026

There is a growing sense of complacency as central Illinois remains under the influence of atmospheric blocking. Over the last 7 to 10 days, this persistent pattern has continuously steered frontal systems away from the area. As a result, the region is undergoing one of its warmest Octobers on record, with Peoria, Lincoln, and Springfield currently ranking 3rd, 5th, and 10th warmest, respectively.

It will be more of the same through the front half of this week. The western trough is forecast to open and lift across the Rockies tonight, then pivot across the Northern Plains by Monday night. While this trough will be effective in de-amplifying or flattening the upper-level blocking pattern, it will not be quite enough to break it down completely. The main surface front will remain displaced to our north, and the net effect will be another warm and dry day on Monday with highs well into the 70s despite increasing high clouds.

An auxiliary shortwave trough moves out of the Southern Plains toward the Ozarks on Tuesday. Although it delivers minor synoptic lift along with a slight surge of Gulf moisture to the central U.S. Tuesday night into Wednesday morning, our local area stays positioned on the western edge of dry surface high pressure. We therefore anticipate any high-based showers to remain off to our north and west over Iowa.

Following this midweek disturbance, upper-level ridging quickly builds back in, promoting dry weather and unseasonable warmth through at least Thursday afternoon. Because a northern-stream shortwave tries to push a backdoor cold front into central Illinois on Thursday, we do carry low probabilities of rain. High-based, scattered showers remain possible near and north of Interstate 74 as the front sags southward, though both blended (NBM) and global ensemble (LREF Mean) guidance suggest rain is unlikely (10% to 30% chance). Any light precipitation that does land will fail to meaningfully impact the ongoing extended dry stretch.

Otherwise, the surface front is forecast to retreat back northward by Friday, ensuring high temperatures will stay in the upper 70s to near 80 degrees. This continued thermal ridge will comfortably lock in what stands as one of the warmest Octobers on record.

Aviation

Issued at 1146 AM CDT Sun Oct 25 2026

VFR conditions will persist through this TAF cycle as the regional terminals maintain mostly clear skies and light winds due to a ridge of high pressure enveloping much of the area.

Ilx Watches

None.