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 °C. As the month progressed, temperatures tended to moderately rise, reaching an average of 26 °C 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°/9°
Temperatures
25 km/h
Avg max wind
43 %
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 9°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Casper during September?
In September, Casper can expect light to moderate rainfall, totaling 31.9 mm across approximately 2 days. Occasional showers are possible, and planning ahead for them could be helpful.
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 💧
Typically, Casper has 2 rainy days in September with a total of 31.9 mm of rainfall.
UV exposure in Casper during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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