textproduct: Central Illinois

KEY MESSAGES

- We have high confidence that hot and humid conditions will build this weekend. Peak heat indices will approach 100-105 F across much of Central Illinois on Sunday and Monday.

- Thunderstorms will remain isolated and disorganized through Monday, primarily posing a threat for localized heavy rain. The risk for organized severe thunderstorms, including damaging winds and large hail, increases Tuesday and Wednesday.

- A cold front will sweep through the region late next week, providing relief from the heat. We have high confidence in the arrival of cooler and drier air, though the exact temperature drop remains uncertain.

LATE NEXT WEEK: TROUGHING & PATTERN CHANGE

By late next week, a broader pattern transition appears likely to take shape. Ensembles show an amplifying upper trough consolidating over the Great Lakes, pushing a surface cold front south through Illinois and allowing a continental polar (cP) air mass to gradually build into the Midwest. This transition will usher in a cooler, drier, and more stable air mass. However, ensemble cluster analysis (GEFS/EPS) continues to exhibit notable spread regarding the trough's ultimate amplitude and southward extent, leaving some uncertainty regarding the exact magnitude of the late-week cooling and dew point suppression.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 535 AM CDT Fri Aug 7 2026

Low stratus and patchy dense fog will gradually mix away this morning with increasing solar insolation. VFR conditions will return to all regional terminals by 18z and remain unrestricted through the rest of this TAF cycle.

Surface winds will slowly veer from south to southwest through the TAF period, largely staying within the 5-8 kt range.

ILX WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 8 AM CDT this morning for ILZ038- 043>046-052>057-061>063.