Johnson County (Iowa City)
September
Weather in Johnson County, Iowa for September 2026
Your guide to Johnson County weather in September - trends and predictions
So far, September 2026 in Johnson County shows a warmer trend than usual by 3.2 °F.
The forecast for the next days in Johnson County predicts a temperature of 21.1 °F, which is cooler than the historical average.
In general, the average temperature in Johnson County at the beginning of September is 27 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 18.4 °F by the end of September.
With an average of 5 rainy days, Johnson County experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
25
Dry days
5
Rainy days
0
Snow days
26°/14°
Temperatures
17 km/h
Avg max wind
69 %
Avg humidity
Johnson County Weather September
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Temperatures trend during September in Johnson County
See the weather trend as well as the moving average line
September weather in Johnson County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 29° /16° | 0 mm | 7 | |
| Sept. 2 | Sunny | 29° /15° | 0.1 mm | 5 | |
| Sept. 3 |  Partly cloudy | 27° /15° | 10.4 mm | 6 | |
| Sept. 4 | Sunny | 29° /12° | 0 mm | 7 | |
| Sept. 5 | Partly cloudy | 29° /16° | 0 mm | 6 | |
| Sept. 6 |  Overcast | 23° /12° | 0.1 mm | 4 | |
| Sept. 7 | Sunny | 23° /9° | 0 mm | 4 | |
| Sept. 8 | Overcast | 27° /11° | 0 mm | 4 | |
| Sept. 9 | Sunny | 27° /14° | 136.7 mm | 5 | |
| Sept. 10 | Sunny | 27° /14° | 0 mm | 6 | |
| Sept. 11 | Sunny | 29° /14° | 0 mm | 7 | |
| Sept. 12 | Sunny | 30° /15° | 0 mm | 7 | |
| Sept. 13 | Overcast | 27° /16° | 1.7 mm | 5 | |
| Sept. 14 | Partly cloudy | 29° /16° | 0.8 mm | 6 | |
| Sept. 15 |  Cloudy | 28° /18° | 9.4 mm | 5 | |
| Sept. 16 | Overcast | 21° /16° | 4.9 mm | 3.6 | |
| Sept. 17 |  Mist | 25° /19° | 4.4 mm | 3.7 | |
| Sept. 18 | Sunny | 27° /18° | 9.5 mm | 4.2 | |
| Sept. 19 | Overcast | 26° /21° | 3.9 mm | 5 | |
| Sept. 20 |  Light rain shower | 24° /17° | 19.4 mm | 5 | |
| Sept. 21 | Patchy rain possible | 21° /17° | 10.6 mm | 5 | |
| Sept. 22 | Sunny | 25° /16° | 0 mm | 6 | |
| Sept. 23 | Light rain shower | 24° /18° | 20.6 mm | 5 | |
| Sept. 24 | Patchy rain possible | 19° /16° | 1.8 mm | 4 | |
| Sept. 25 | Sunny | 21° /16° | 0.7 mm | 6 | |
| Sept. 26 | Sunny | 18° /12° | 0.3 mm | 5 | |
| Sept. 27 | Sunny | 15° /8° | 0 mm | 5 | |
| Sept. 28 | Sunny | 16° /8° | 0 mm | 5 | |
| Sept. 29 | Overcast | 13° /9° | 4.5 mm | 3 | |
| Sept. 30 | Overcast | 27° /14° | 0 mm | 6 | |
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Important Notice
Our weather forecast for Johnson 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 Johnson County forecast closer to your planned date for the most up-to-date weather information.
Change Month
Johnson County in September - FAQ
What are the expected maximum and minimum temperatures in Johnson County during September?
Enjoy moderate daytime temperatures of up to 26° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Johnson County during September?
Moderate rainfall is anticipated in Johnson County during September, with a total of 74.3 mm spread over approximately 5 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Johnson County during September?
The average wind speed in Johnson County during September is 17 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Johnson County
Explore the daily rainfall trends and prepare for Johnson Countys September weather 💧
Typically, Johnson County has 5 rainy days in September with a total of 74.3 mm of rainfall.
UV exposure in Johnson County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Where is Johnson County?Get accurate weather forecasts for Johnson County, located at latitude 41.661 and longitude -91.53. Stay updated with localized weather information tailored for Johnson County.
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