September weather forecastCheyenne, WY
September
Weather in September
Following the warmth of August, September brings a definitive shift in Cheyenne's weather pattern. A noticeable decrease in daylight and temperature signals the advent of autumn. The slightly cooler weather means that leaves start changing colors, dressing the city in shades of orange, yellow, and red. Although noticeably milder than the peak summer months, the weather remains quite comfortable for outdoor activities.Temperature
In September, the average high-temperature marginally decreases from a moderately hot 81.1°F (27.3°C) in August to a still warm 73.8°F (23.2°C). Cheyenne throughout September, experiences an average nighttime temperature of 52.3°F (11.3°C).Humidity
In Cheyenne, the average relative humidity in September is 44%.Rainfall
In September, the rain falls for 8.4 days. Throughout September, 0.87" (22mm) of precipitation is accumulated. Throughout the year, there are 116 rainfall days, and 14.57" (370mm) of precipitation is accumulated.Snowfall
In Cheyenne, snow does not fall in June through September.Daylight
In Cheyenne, the average length of the day in September is 12h and 27min.On the first day of the month, sunrise is at 6:26 am and sunset at 7:31 pm. On the last day of September, sunrise is at 6:55 am and sunset at 6:42 pm MDT.
Sunshine
In September, the average sunshine is 10.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: In September, a regular UV index of 4 translates into these guidelines:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. The midday Sun can be harmful due to its potent UV radiation; seek shade and reduce exposure. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Cheyenne, WY
- Average high temperature in September: 73.8°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is December (34.7°F).
- Average low temperature in September: 52.3°F
The month with the highest average low temperature is July (59.9°F).
The coldest month (with the lowest average low temperature) is December (20.3°F).
Average pressure in September
Cheyenne, WY
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.87"Hg).
Average wind speed in September
Cheyenne, WY
- Average wind speed in September: 9.6mph
The windiest month (with the highest average wind speed) is January (14.2mph).
The calmest month (with the lowest average wind speed) is August (8.7mph).
Average humidity in September
Cheyenne, WY
- Average humidity in September: 44%
The month with the highest relative humidity is February (64%).
The month with the lowest relative humidity is August (43%).
Average rainfall in September
Cheyenne, WY
- Average rainfall in September: 0.87"
The wettest month (with the highest rainfall) is May (2.95").
The driest month (with the least rainfall) is January (0.43").
Average rainfall days in September
Cheyenne, WY
- Average rainfall days in September: 8.4 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is January (4.7 days).
Average snowfall in September
Cheyenne, WY
- Average snowfall in September: 0"
The month with the highest snowfall is March (6.06").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Cheyenne, WY
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (11.3 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Cheyenne, WY
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in September: 10h and 42min
The months with the most sunshine are July and August (Average sunshine: 11h and 36min).
The month with the least sunshine is February (Average sunshine: 6h and 30min).
Average sunshine days in September
Cheyenne, WY
- Average sunshine days in September: 19 days
The month with the most sunshine days is January (20.7 days).
The month with the least sunshine days is April (9.3 days).
Average UV index in September
Cheyenne, WY
- Average UV index in September: 4
The months with the highest UV index are July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Cheyenne, WY
- Average cloud cover in September: 18
The months with the most cloud cover are April and May (Cloud cover 32).
The month with the least cloud cover is September (Cloud cover 18).
Average visibility in September
Cheyenne, WY
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
