September weather forecast
Cheyenne, WY

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A sunny day in front of the State Capitol building in Cheyenne, Wyoming
A sunny day in front of the State Capitol building in Cheyenne, Wyoming

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.
Updated: Jun 26, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures?

During September, Cheyenne experiences an average high-temperature of 73.8°F (23.2°C) and a low-temperature of 52.3°F (11.3°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, in August is estimated at 80.6°F (27°C).

What is the average humidity in September?

In September, the average relative humidity in Cheyenne is 44%.

How many days does it rain in September?

In Cheyenne, in September, during 8.4 rainfall days, 0.87" (22mm) of precipitation is typically accumulated.

When it does not snow?

In Cheyenne, snow does not fall in June through September.

Does it snow in September?

In Cheyenne, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Cheyenne have in September?

In Cheyenne, the average day length in September is 12h and 27min.

When is the sunrise / sunset in September?

In September, on the first day of the month, sunrise is at 6:26 am and sunset at 7:31 pm. On the last day of the month, in Cheyenne, sunrise is at 6:55 am and sunset at 6:42 pm MDT.

How many hours of sunshine does Cheyenne have in September?

In September, the average sunshine duration is 10.7h.

What is the UV index reading in September?

In Cheyenne, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health threat from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Cheyenne, WY

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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 / Average sunshine in September - Cheyenne, WY
  • Average daylight in September: 12h and 3min

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 4min

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 - 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 - 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 - 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 - 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).

Cheyenne, Wyoming, USA

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