Heat expands across the Desert Southwest, Plains, Mississippi Valley and Midwest into Monday. Fire weather concerns continue for portions of the Intermountain West. Active monsoonal moisture fuels thunderstorms over the Southwest with possible flash flooding. Tropical cyclone Fausto in the Pacific, should weaken as it approaches Hawaii; Dangerous surf, swells and rip currents are expected. Read More >
Overview
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| CoCoRaHS Observer Monthly Precipitation Summary |
Chicago Daily Climate Data for September 2025
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| Daily high and low temperatures observed at Chicago-O'Hare Airport in September 2025 plotted relative to the normal and record high and low temperatures for each date. |
Rockford Daily Climate Data for September 2025
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| Daily high and low temperatures observed at Rockford Airport in September 2025 plotted relative to the normal and record high and low temperatures for each date. |
September 2025 Climate Summary for Chicago and Rockford
Public Information Statement National Weather Service Chicago IL 953 AM CDT Wed Oct 1 2025 /1053 AM EDT Wed Oct 1 2025/ ...A Look Back at the Climate for the Month of September 2025 for Chicago and Rockford... At Chicago, the average high temperature was 78.9 degrees, which is 3.4 degrees above normal. The average low temperature was 59.7 degrees, which is 2.6 degrees above normal. The mean average temperature for the month was 69.3 degrees, which is 3.0 degrees above normal. 0.49 inches of liquid precipitation were recorded, which is 2.70 inches below normal. The following top ten monthly records were set for Chicago this past September: **Tied 7th driest September on record with 0.49 inches of liquid precipitation. At Rockford, the average high temperature was 79.6 degrees, which is 4.3 degrees above normal. The average low temperature was 53.4 degrees, which is 0.1 degrees below normal. The average temperature for the month was 66.5 degrees, which is 2.1 degrees above normal. 1.05 inches of liquid precipitation were recorded, which is 2.57 inches below normal. No daily or top ten monthly records were set for Rockford during this past September. .................................................................. Chicago's climatic period of record dates back to: 1871 for precipitation 1872 for temperatures 1884 for snowfall Rockford's climatic period of record dates back to: 1905 for temperatures, precipitation, and snowfall $$
Latest Monthly Climate Report: Chicago (O'Hare) | Rockford
Events
No significant weather events occurred in northern Illinois and northwest Indiana this past September.
NWS Chicago Science and Past Events Page
Additional Information
Local Climate Resources:
State/Regional/National Climate Resources:
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