Decatur (IL)
September
Weather in Decatur, Illinois for September 2026
Your guide to Decatur weather in September - trends and predictions
In general, the average temperature in Decatur at the beginning of September is 25.1 °F. As the month progressed, temperatures tended to slightly decrease, reaching an average of 25 °F by the end of September.
With an average of 3 rainy days, Decatur experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
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27
Dry days
3
Rainy days
0
Snow days
26°/15°
Temperatures
19 km/h
Avg max wind
61 %
Avg humidity
Decatur Weather September
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Temperatures trend during September in Decatur
See the weather trend as well as the moving average line
September weather in Decatur day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 28° /13° | 0 mm | 7 | |
| Sept. 2 | Sunny | 26° /11° | 0 mm | 7 | |
| Sept. 3 |  Overcast | 25° /13° | 0 mm | 6 | |
| Sept. 4 | Sunny | 26° /12° | 2.6 mm | 7 | |
| Sept. 5 | Sunny | 25° /14° | 0 mm | 6 | |
| Sept. 6 |  Mist | 24° /10° | 0.2 mm | 5 | |
| Sept. 7 | Sunny | 22° /7° | 0 mm | 6 | |
| Sept. 8 |  Partly cloudy | 23° /6° | 0 mm | 6 | |
| Sept. 9 | Sunny | 26° /9° | 0 mm | 6 | |
| Sept. 10 | Sunny | 29° /12° | 0 mm | 8 | |
| Sept. 11 | Sunny | 32° /15° | 0 mm | 8 | |
| Sept. 12 | Sunny | 31° /15° | 0 mm | 8 | |
| Sept. 13 |  Light rain | 29° /17° | 0.8 mm | 7 | |
| Sept. 14 | Partly cloudy | 34° /18° | 0 mm | 8 | |
| Sept. 15 |  Patchy rain possible | 32° /20° | 0.1 mm | 7 | |
| Sept. 16 | Sunny | 32° /16° | 0 mm | 8 | |
| Sept. 17 |  Cloudy | 29° /14° | 0 mm | 7 | |
| Sept. 18 | Sunny | 29° /14° | 0 mm | 7 | |
| Sept. 19 | Cloudy | 30° /16° | 4.1 mm | 7 | |
| Sept. 20 | Overcast | 28° /17° | 3.5 mm | 6 | |
| Sept. 21 | Fog | 27° /16° | 27.1 mm | 6 | |
| Sept. 22 |  Heavy rain at times | 24° /17° | 4.5 mm | 6 | |
| Sept. 23 | Overcast | 24° /17° | 1.6 mm | 6 | |
| Sept. 24 |  Moderate or heavy rain shower | 20° /16° | 154.4 mm | 5 | |
| Sept. 25 | Mist | 23° /12° | 0 mm | 5 | |
| Sept. 26 | Overcast | 24° /11° | 0 mm | 5 | |
| Sept. 27 | Overcast | 26° /15° | 0 mm | 6 | |
| Sept. 28 | Overcast | 28° /15° | 0 mm | 7 | |
| Sept. 29 | Overcast | 27° /17° | 0 mm | 7 | |
| Sept. 30 | Mist | 27° /17° | 0 mm | 6 | |
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Important Notice
Our weather forecast for Decatur 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 Decatur forecast closer to your planned date for the most up-to-date weather information.
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Decatur in September - FAQ
What are the expected maximum and minimum temperatures in Decatur during September?
During September, expect a variety of temperatures with highs around 26° and lows near 15°, suitable for diverse activities and preferences.
How much rainfall should be expected in Decatur during September?
Significant rainfall exceeding 160.4 mm is expected in Decatur during September, occurring over more than 3 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Decatur during September?
The average wind speed in Decatur during September is 19 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Decatur
Explore the daily rainfall trends and prepare for Decaturs September weather 💧
UV exposure in Decatur during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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