September weather forecast and climate
Cheyenne, WY

A sunny day in the front of the State Capitol building in Cheyenne, Wyoming
A sunny day in the front of the State Capitol building in Cheyenne, Wyoming
September transitions Cheyenne into autumn. The weather is characterized by a slight decrease in the temperature to the range of 44.6°F (7°C) and 71.6°F (22°C). The summer weather is experienced until the very end of September.
The sunsets arrive earlier, reducing the daylight hours to twelve. Most afternoons experience rainfall for approximately nine days to collect relatively low precipitation of 1.5" (38.1mm). Most days are marked by tolerable warmth, moderate rainfall, and up to eleven hours of sunshine per day.
Crowds remain high, while the weather is warm and summer-like.

What is the temperature in September in Cheyenne?

In September, in Cheyenne, the average high-temperature is 71.8°F (22.1°C), and the average low-temperature is 44.8°F (7.1°C).

How many days does it rain in September in Cheyenne?

In Cheyenne, in September, during 8.3 rainfall days, typically 1.5" (37.6mm) of precipitation is accumulated.

When does it start snowing in Cheyenne?

September is the first month it typically snows in Cheyenne. Throughout September, in the average 0.7 snowfall days, it receives 1.3" (33mm) of snow.
Average temperature in September - Cheyenne, WY
  • Average high temperature in September: 22.1°C

The warmest month (with the highest average high temperature) is July (28.6°C).
The month with the lowest average high temperature is December (3.4°C).

  • Average low temperature in September: 7.1°C

The month with the highest average low temperature is July (13.1°C).
The coldest month (with the lowest average low temperature) is December (-8.2°C).

Average humidity in September - Cheyenne, WY
  • Average humidity in September: 51.5%

The month with the highest relative humidity is March (56.1%).
The month with the lowest relative humidity is October (50%).

Average rainfall in September - Cheyenne, WY
  • Average rainfall in September: 37.6mm

Wettest months (with the highest rainfall) are May and June (59.4mm).
The driest month (with the lowest rainfall) is January (8.4mm).

Average rainfall days in September - Cheyenne, WY
  • Average rainfall days in September: 8.3 days

The month with the highest number of rainy days is May (12.4 days).
The month with the lowest number of rainy days is January (4.9 days).

Average snowfall in September - Cheyenne, WY
  • Average snowfall in September: 33mm

The month with the highest snowfall is March (287mm).
Months with the lowest snowfall are June, July and August (0mm).

Average snowfall days in September - Cheyenne, WY
  • Average snowfall days in September: 0.7 days

The month with the highest number of snowfall days is March (7.8 days).
Months with the lowest number of snowfall days are July and August (0 days).

Average daylight in September / Average sunshine in September - Cheyenne, WY
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.1h).
The month with shortest days is December (Average daylight: 9.3h).

  • Average sunshine in September: 8.7h

The month with most sunshine is July (Average sunshine: 10.2h).
The month with least sunshine is December (Average sunshine: 5.7h).

Average UV index in September - Cheyenne, WY
  • Average UV index in September: 7

Months with the highest UV index are June and July (UV index 10).
The month with the lowest UV index is December (UV index 1).

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