September weather forecast
Illinois, USA

September marks the dawn of fall in Illinois, introducing a palpable shift in temperatures and a transformation in the landscape. The northern areas, bordering Wisconsin, usher in daytime temperatures that sit between the upper 60s°F to mid-70s°F. On the other hand, the southern regions, near Kentucky, enjoy warmer days, often in the mid to upper 70s°F.

Chicago, known for its diverse cultural and recreational offerings, is awash in a palette of changing colors. Lake Michigan, though its cooling influence persists, witnesses a drop in beach activities as the water temperature begins to descend. The city parks, meanwhile, become a canvas of golds, reds, and oranges, making them a haven for both residents and tourists.

September nights are crisp, with temperatures usually ranging from the mid-50s°F to low 60s°F. The cooling nights and decreasing daylight herald the steady march toward winter.

Comparing September with August, there's a clear decrease in temperatures, signifying the shift from summer to fall. Rain showers become more sporadic, and while thunderstorms can occur, they're less intense than the summer variants. By September's close, Illinois is firmly entrenched in the embrace of autumn, anticipating the cooler touch of October.

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• Chicago - September »
  September is a transitional month in Chicago with a shift from warm summer days to the mild and pleasant days of fall. In September, the average ocean temperature in Chicago, Illinois, is 68.5°F (20.3°C).
• Aurora - September »
  In Aurora, during September, the rain falls for 8.8 days and regularly aggregates up to 0.87" (22mm) of precipitation. In Aurora, entering September brings a subtle temperature decrement, reducing from August's 79.3°F (26.3°C) to a still warm 73.6°F (23.1°C).
• Rockford - September »
  On the first day of September in Rockford sunrise is at 6:22 am and sunset at 7:29 pm. In Rockford snow does not fall in May through September.
• Joliet - September »
  On the last day of September, in Joliet, sunrise is at 6:48 am and sunset at 6:35 pm CDT. With the arrival of September, Joliet notices a mild change in the average high-temperature, sliding from August's moderately hot 80.1°F (26.7°C) to a still warm 74.7°F (23.7°C).
• Naperville - September »
  On the first day of September in Naperville, sunrise is at 6:19 am and sunset at 7:25 pm. September ushers in a minute temperature change in Naperville, with average high-temperatures reducing from August's 80.1°F (26.7°C) to a still warm 73.8°F (23.2°C).
• Springfield - September »
  In Springfield in September, it is raining for 12.3 days, with typically 2.28" (58mm) of accumulated precipitation. The onset of September in Springfield notes an average high-temperature of a still warm 77.4°F (25.2°C), subtly shifted from August's 81.9°F (27.7°C).
• Peoria - September »
  On the first day of September in Peoria sunrise is at 6:26 am and sunset at 7:30 pm. In Peoria in September, it is raining for 10.5 days, with typically 1.42" (36mm) of accumulated precipitation.
• Elgin - September »
  In Elgin in September, it is raining for 12.5 days, with typically 1.69" (43mm) of accumulated precipitation. In Elgin, in September, it is raining for 12.5 days, with typically 1.69" (43mm) of accumulated precipitation.
• Waukegan - September »
  On the first day of September in Waukegan, sunrise is at 6:17 am and sunset at 7:24 pm. In Waukegan, during September, the rain falls for 12.7 days and regularly aggregates up to 1.73" (44mm) of precipitation.
• Champaign - September »
  On the first day of September in Champaign, sunrise is at 6:21 am and sunset at 7:24 pm. On the first day of September in Champaign, sunrise is at 6:21 am and sunset at 7:24 pm.
• Cicero - September »
  In Cicero, Illinois, during September, the rain falls for 11.2 days and regularly aggregates up to 1.14" (29mm) of precipitation. September marks the gradual transition from the hot summer months to the slightly cooler autumn season in Cicero.
• Bloomington - September »
  In Bloomington in September, it is raining for 12.2 days, with typically 1.5" (38mm) of accumulated precipitation. On the first day of September in Bloomington, sunrise is at 6:24 am and sunset at 7:27 pm.