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Weather in Cook County for September 2025

Your guide to Cook County weather in September - trends and predictions
  • In general, the average temperature in Cook County at the beginning of September is 26.7 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 21.7 °F by the end of September.

  • Cook County sees moderate rainfall in September, averaging 10 rainy days.

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Average dry days
20
Dry days
Average rainy days
10
Rainy days
Average snowy days
0
Snow days
Average temperatures
24°/17°
Temperatures
Average wind speed
19 km/h
Avg max wind
Average humidity
68 %
Avg humidity

Cook County in September average weather

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Temperatures trend during September in Cook County

See the weather trend as well as the moving average line

September weather day by day

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Date Weather Temperatures Rain UV More
Sept. 1 Sunny
Sunny
25° /17° 0 mm 7
Sept. 2 Partly cloudy
Partly cloudy
27° /18° 0 mm 7
Sept. 3 Partly cloudy
Partly cloudy
29° /17° 0 mm 7
Sept. 4 Sunny
Sunny
30° /19° 0 mm 8
Sept. 5 Patchy rain possible
Patchy rain possible
31° /21° 0.6 mm 8
Sept. 6 Light rain shower
Light rain shower
26° /18° 5 mm 6
Sept. 7 Patchy rain possible
Patchy rain possible
19° /13° 0.3 mm 5
Sept. 8 Overcast
Overcast
21° /14° 0 mm 6
Sept. 9 Cloudy
Cloudy
25° /16° 0 mm 6
Sept. 10 Partly cloudy
Partly cloudy
26° /17° 0 mm 7
Sept. 11 Moderate or heavy rain shower
Moderate or heavy rain shower
25° /18° 28.6 mm 6
Sept. 12 Cloudy
Cloudy
23° /17° 0 mm 6
Sept. 13 Light rain shower
Light rain shower
23° /17° 0.6 mm 5
Sept. 14 Overcast
Overcast
23° /17° 0 mm 6
Sept. 15 Cloudy
Cloudy
27° /18° 0 mm 6
Sept. 16 Thundery outbreaks possible
Thundery outbreaks possible
26° /18° 1.2 mm 6
Sept. 17 Light rain shower
Light rain shower
21° /16° 1.2 mm 5
Sept. 18 Cloudy
Cloudy
21° /16° 0 mm 5
Sept. 19 Heavy rain
Heavy rain
22° /16° 10.1 mm 5
Sept. 20 Thundery outbreaks possible
Thundery outbreaks possible
28° /18° 0.1 mm 6
Sept. 21 Overcast
Overcast
27° /19° 0 mm 7
Sept. 22 Fog
Fog
24° /17° 18 mm 6
Sept. 23 Sunny
Sunny
21° /16° 0 mm 5
Sept. 24 Overcast
Overcast
21° /15° 0 mm 5
Sept. 25 Patchy rain possible
Patchy rain possible
23° /16° 0.1 mm 5
Sept. 26 Patchy light rain with thunder
Patchy light rain with thunder
23° /15° 12.8 mm 6
Sept. 27 Light rain shower
Light rain shower
21° /16° 4.7 mm 5
Sept. 28 Patchy rain possible
Patchy rain possible
20° /17° 0.1 mm 5
Sept. 29 Mist
Mist
21° /17° 5.3 mm 5
Sept. 30 Fog
Fog
23° /17° 0 mm 6
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Important Notice
Our weather forecast for Cook County in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Cook County forecast closer to your planned date for the most up-to-date weather information.

Cook County in September - FAQ

What are the expected maximum and minimum temperatures in Cook County during September?
During September, expect a variety of temperatures with highs around 24° and lows near 17°, suitable for diverse activities and preferences.
How much rainfall should be expected in Cook County during September?
Significant rainfall exceeding 127.2 mm is expected in Cook County during September, occurring over more than 10 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Cook County during September?
The average wind speed in Cook County during September is 19 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Cook County

Explore the daily rainfall trends and prepare for Cook Countys September weather 💧

UV exposure in Cook County during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Location coordinates Where is Cook County?

Get accurate weather forecasts for Cook County, located at latitude 41.85 and longitude -87.65. Stay updated with localized weather information tailored for Cook County.

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