Illinois Fall Heads for Warmest Season on Record

Illinois recorded its warmest September on record and October ranked third-highest, with fall running warmer and drier than normal.

Updated on Nov. 10, 2026 in Current Conditions

Wide Illinois farm field in late autumn with dry golden stubble and a distant line of trees still holding some green and amber leaves under warm light. — Illinois recorded its warmest September on record at an average of 73 degrees Fahrenheit, with fall running warmer and drier than normal across the state. AI Illustration. Upload story photo >

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Illinois had its warmest September on record, averaging 73 degrees Fahrenheit, and is on track for the warmest fall on record in the state. The season has also been drier than average, with about 2.5 to 3 inches less rainfall than normal.

Why it matters

The persistent warmth and dryness reflect patterns typical of an El Niño season in Illinois, and the season's warm conditions extend across Arkansas, Kansas and Oklahoma, which also recorded their warmest September on record. Residents across the state are seeing the effects in changing seasonal timing.

Illinois September averaged 73 degrees Fahrenheit, more than 6 degrees above the 20th-century average, while October ran slightly more than 7 degrees above normal and ranked as the state's third-highest October on record. Fall rainfall has been about 2.5 to 3 inches below average, and whether November will continue the warm trend remains unresolved.

The details

Meteorologists define fall as the period from Sept. 1 to Nov. 30, and this season has been warmer and drier than normal across Illinois. Maple and hickory trees on state campuses dropped leaves later than usual, and some lilac shrubs have reflowered instead of preparing for dormancy.

September 2026: Illinois records its warmest September on record.
October 2026: Illinois posts its third-highest October average temperature on record.
November 2026: A warmer-than-normal month remains possible as the season continues.

Seasonal Patterns

This fall's warmth and dryness follow the typical El Niño pattern seen in Illinois, rather than breaking from it. The season's conditions match the shape of a documented El Niño year, placing this record fall within a recognizable regional cycle.

Residents should expect continued warm, dry conditions in November if the pattern holds, which may affect outdoor watering and fire-risk planning. Those managing lawns, gardens, or landscaping should account for the later leaf drop and the early reflowering of shrubs.

The takeaway

A record-warm, dry fall reshapes seasonal timing across Illinois, from delayed leaf drop to shrubs blooming out of season. Watching whether November continues the trend will show whether this pattern is holding.