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

The advent of September in Cheyenne brings a slight shift in average high-temperature, moving from a moderately hot 81.1°F (27.3°C) in August to a still warm 73.8°F (23.2°C). Throughout the nights in September, Cheyenne experiences an average low-temperature of 52.3°F (11.3°C).

Humidity

The average relative humidity in September in Cheyenne, Wyoming, is 44%.

Rainfall

In Cheyenne, in September, during 8.4 rainfall days, 0.87" (22mm) of precipitation is typically accumulated. In Cheyenne, during the entire year, the rain falls for 116 days and collects up to 14.57" (370mm) of precipitation.

Snowfall

June through September are months without snowfall.

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 in Cheyenne is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: A maximum UV index of 4 in September translates into the following recommendations:
Be vigilant - Preventing sunburn is recommended. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
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Frequently asked questions

What are the temperatures in Cheyenne in September?

In September, the average high-temperature and low-temperature in Cheyenne, Wyoming, are 73.8°F (23.2°C) and 52.3°F (11.3°C) respectively. The average heat index (a.k.a. 'real feel', 'felt air 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 Cheyenne?

The average relative humidity in September in Cheyenne, Wyoming, is 44%.

How much does it rain in Cheyenne 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?

June through September are months without snowfall in Cheyenne.

Does it snow in Cheyenne in September?

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

How many hours of daylight does Cheyenne have in September?

The average day length in September in Cheyenne, Wyoming, is 12h and 27min.

When is the sunrise / sunset in September in Cheyenne?

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

How many hours of sunshine does Cheyenne have in September?

In Cheyenne, Wyoming, the average sunshine duration in September is 10.7h.

What is the UV index intensity in September in Cheyenne?

In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unprotected exposure to 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).

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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).

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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).

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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%).

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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").

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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).

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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").

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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).

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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).

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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).

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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).

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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).

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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).

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Cheyenne, Wyoming, USA

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