Casper (WY)
September
Weather in Casper, Wyoming for September 2026
Your guide to Casper weather in September - trends and predictions
In general, the average temperature in Casper at the beginning of September is 25.1 °F. As the month progressed, temperatures tended to moderately rise, reaching an average of 26 °F by the end of September.
With an average of 2 rainy days, Casper experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
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28
Dry days
2
Rainy days
0
Snow days
25°/10°
Temperatures
25 km/h
Avg max wind
37 %
Avg humidity
Casper Weather September
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Temperatures trend during September in Casper
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September weather in Casper day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 27° /10° | 0 mm | 7 | |
| Sept. 2 | Sunny | 28° /10° | 0 mm | 7 | |
| Sept. 3 | Sunny | 26° /11° | 0 mm | 7 | |
| Sept. 4 | Sunny | 27° /11° | 0 mm | 7 | |
| Sept. 5 |  Overcast | 19° /8° | 0 mm | 4 | |
| Sept. 6 | Sunny | 22° /4° | 0 mm | 6 | |
| Sept. 7 |  Thundery outbreaks possible | 27° /8° | 0 mm | 6 | |
| Sept. 8 |  Partly cloudy | 27° /11° | 0 mm | 7 | |
| Sept. 9 |  Cloudy | 29° /11° | 0 mm | 7 | |
| Sept. 10 | Sunny | 30° /12° | 0 mm | 8 | |
| Sept. 11 |  Patchy rain possible | 29° /12° | 0.1 mm | 7 | |
| Sept. 12 | Sunny | 26° /11° | 0 mm | 7 | |
| Sept. 13 | Sunny | 23° /10° | 0 mm | 6 | |
| Sept. 14 | Overcast | 25° /8° | 0 mm | 6 | |
| Sept. 15 | Partly cloudy | 27° /10° | 0 mm | 6 | |
| Sept. 16 |  Heavy rain at times | 23° /10° | 0.9 mm | 5 | |
| Sept. 17 |  Moderate or heavy rain shower | 17° /10° | 26.5 mm | 4 | |
| Sept. 18 | Sunny | 20° /8° | 3.8 mm | 5 | |
| Sept. 19 | Sunny | 24° /7° | 0 mm | 6 | |
| Sept. 20 | Sunny | 26° /7° | 0 mm | 7 | |
| Sept. 21 | Overcast | 20° /8° | 0 mm | 5 | |
| Sept. 22 | Sunny | 20° /5° | 0.6 mm | 5 | |
| Sept. 23 | Cloudy | 20° /5° | 0 mm | 5 | |
| Sept. 24 | Sunny | 23° /7° | 0 mm | 6 | |
| Sept. 25 | Sunny | 28° /7° | 0 mm | 8 | |
| Sept. 26 | Sunny | 28° /11° | 0 mm | 8 | |
| Sept. 27 | Sunny | 27° /9° | 0 mm | 7 | |
| Sept. 28 | Partly cloudy | 28° /10° | 0 mm | 8 | |
| Sept. 29 | Sunny | 28° /10° | 0 mm | 7 | |
| Sept. 30 | Sunny | 20° /6° | 0 mm | 6 | |
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Important Notice
Our weather forecast for Casper 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 Casper forecast closer to your planned date for the most up-to-date weather information.
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Casper in September - FAQ
What are the expected maximum and minimum temperatures in Casper during September?
Enjoy moderate daytime temperatures of up to 25° and cooler nights around 10°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Casper during September?
Expect minimal rainfall in Casper during September, with a total of 11.2 mm over approximately 2 days. This minimal precipitation is unlikely to significantly impact plans.
What are the typical wind conditions in Casper during September?
The average wind speed in Casper during September is 25 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Casper
Explore the daily rainfall trends and prepare for Caspers September weather 💧
UV exposure in Casper during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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