Johnson County (Iowa City)
September
Weather in Johnson County, Iowa for September 2025
Your guide to Johnson County weather in September - trends and predictions
Expect cooler weather in first days of September 2025 in Johnson County with the forecast suggesting a temperature of 24.8 °F, lower than the historical average.
In general, the average temperature in Johnson County at the beginning of September is 26.1 °F. As the month progressed, temperatures tended to moderately fall, reaching an average of 24.6 °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 🌧️
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25
Dry days
5
Rainy days
0
Snow days
26°/13°
Temperatures
17 km/h
Avg max wind
64 %
Avg humidity
Johnson County Weather September
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Temperatures trend during September in Johnson County
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September weather in Johnson County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Partly cloudy | 26° /16° | 0 mm | 5 | |
| Sept. 2 |  Sunny | 29° /17° | 0 mm | 6 | |
| Sept. 3 |  Patchy rain possible | 26° /18° | 3.3 mm | 5 | |
| Sept. 4 | Patchy rain possible | 30° /19° | 2.4 mm | 5 | |
| Sept. 5 |  Mist | 27° /18° | 0.1 mm | 5 | |
| Sept. 6 | Partly cloudy | 21° /16° | 0 mm | 5 | |
| Sept. 7 | Patchy rain possible | 24° /19° | 4.2 mm | 5 | |
| Sept. 8 | Sunny | 23° /7° | 0 mm | 6 | |
| Sept. 9 | Sunny | 27° /12° | 0 mm | 7 | |
| Sept. 10 | Sunny | 28° /13° | 0 mm | 7 | |
| Sept. 11 | Sunny | 30° /14° | 0 mm | 8 | |
| Sept. 12 | Sunny | 30° /16° | 0 mm | 8 | |
| Sept. 13 |  Overcast | 25° /17° | 0.1 mm | 6 | |
| Sept. 14 | Partly cloudy | 30° /17° | 0 mm | 8 | |
| Sept. 15 |  Cloudy | 29° /19° | 0 mm | 6 | |
| Sept. 16 | Sunny | 30° /18° | 0 mm | 8 | |
| Sept. 17 | Sunny | 30° /15° | 0 mm | 8 | |
| Sept. 18 | Overcast | 29° /15° | 0 mm | 6 | |
| Sept. 19 | Overcast | 29° /17° | 17.2 mm | 6 | |
| Sept. 20 | Overcast | 30° /19° | 0.4 mm | 7 | |
| Sept. 21 | Patchy rain possible | 30° /17° | 0.1 mm | 7 | |
| Sept. 22 |  Moderate or heavy rain shower | 21° /14° | 15.5 mm | 5 | |
| Sept. 23 | Partly cloudy | 21° /8° | 1.1 mm | 6 | |
| Sept. 24 | Patchy rain possible | 20° /12° | 0.2 mm | 5 | |
| Sept. 25 | Overcast | 24° /10° | 0 mm | 5 | |
| Sept. 26 | Sunny | 26° /11° | 0 mm | 7 | |
| Sept. 27 | Partly cloudy | 24° /12° | 0 mm | 6 | |
| Sept. 28 | Sunny | 26° /13° | 0 mm | 7 | |
| Sept. 29 | Sunny | 26° /13° | 0 mm | 7 | |
| Sept. 30 | Overcast | 26° /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.
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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 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Johnson County during September?
In September, Johnson County can expect light to moderate rainfall, totaling 35 mm across approximately 5 days. Occasional showers are possible, and planning ahead for them could be helpful.
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 💧
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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