Waterloo (IA)
September
Weather in Waterloo, Iowa for September 2026
Your guide to Waterloo weather in September - trends and predictions
So far, September 2026 in Waterloo shows a warmer trend than usual by 2.1 °F.
The forecast for the next days in Waterloo predicts a temperature of 21.5 °F, which is cooler than the historical average.
In general, the average temperature in Waterloo at the beginning of September is 25.1 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 22.3 °F by the end of September.
Waterloo experiences moderate rainfall in September, with an average of 7 rainy days and a total precipitation of 45.3 mm.
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Temperatures
Rain 🌧️
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23
Dry days
7
Rainy days
0
Snow days
25°/13°
Temperatures
18 km/h
Avg max wind
70 %
Avg humidity
Waterloo Weather September
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Temperatures trend during September in Waterloo
See the weather trend as well as the moving average line
September weather in Waterloo day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 26° /17° | 0.1 mm | 5 | |
| Sept. 2 | Sunny | 27° /15° | 0 mm | 7 | |
| Sept. 3 | Sunny | 26° /15° | 1.6 mm | 6 | |
| Sept. 4 | Sunny | 27° /12° | 0 mm | 6 | |
| Sept. 5 |  Patchy rain possible | 26° /14° | 0 mm | 5 | |
| Sept. 6 | Patchy rain possible | 22° /12° | 0 mm | 4 | |
| Sept. 7 | Sunny | 22° /9° | 0 mm | 4 | |
| Sept. 8 |  Overcast | 27° /12° | 3.6 mm | 4 | |
| Sept. 9 | Sunny | 28° /14° | 10.1 mm | 6 | |
| Sept. 10 | Sunny | 27° /13° | 1.8 mm | 7 | |
| Sept. 11 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 12 | Sunny | 27° /15° | 1.6 mm | 6 | |
| Sept. 13 | Overcast | 27° /15° | 0.3 mm | 7 | |
| Sept. 14 | Patchy rain possible | 27° /15° | 4 mm | 5 | |
| Sept. 15 | Patchy rain possible | 28° /18° | 12.9 mm | 5 | |
| Sept. 16 | Overcast | 20° /15° | 1.5 mm | 5.2 | |
| Sept. 17 |  Mist | 23° /18° | 5.1 mm | 2 | |
| Sept. 18 | Light rain shower | 26° /19° | 21.9 mm | 3.4 | |
| Sept. 19 | Overcast | 24° /17° | 6.1 mm | 6.1 | |
| Sept. 20 | Light rain shower | 21° /16° | 20.3 mm | 5 | |
| Sept. 21 | Light rain shower | 17° /15° | 5.4 mm | 4 | |
| Sept. 22 |  Partly cloudy | 18° /13° | 0 mm | 5 | |
| Sept. 23 | Light rain shower | 23° /15° | 3.8 mm | 5 | |
| Sept. 24 | Sunny | 15° /11° | 3 mm | 5 | |
| Sept. 25 | Sunny | 18° /8° | 0 mm | 5 | |
| Sept. 26 | Sunny | 21° /10° | 0 mm | 5 | |
| Sept. 27 | Overcast | 24° /15° | 0 mm | 5 | |
| Sept. 28 | Sunny | 27° /16° | 0 mm | 7 | |
| Sept. 29 | Overcast | 24° /14° | 0 mm | 5 | |
| Sept. 30 | Mist | 27° /13° | 0 mm | 6 | |
| Next | |||||
Important Notice
Our weather forecast for Waterloo 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 Waterloo forecast closer to your planned date for the most up-to-date weather information.
Change Month
Waterloo in September - FAQ
What are the expected maximum and minimum temperatures in Waterloo during September?
Enjoy moderate daytime temperatures of up to 25° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Waterloo during September?
In September, Waterloo can expect light to moderate rainfall, totaling 45.3 mm across approximately 7 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Waterloo during September?
The average wind speed in Waterloo during September is 18 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Waterloo
Explore the daily rainfall trends and prepare for Waterloos September weather 💧
Typically, Waterloo has 7 rainy days in September with a total of 45.3 mm of rainfall.
UV exposure in Waterloo during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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