September weather forecast
Rock Springs, WY

Weather in September

The first month of the autumn, September, is still a pleasant month in Rock Springs, Wyoming, with an average temperature varying between 70.3°F (21.3°C) and 51.3°F (10.7°C).

Temperature

In September, the average high-temperature drops from a moderately hot 79.3°F (26.3°C) in August to an agreeable 70.3°F (21.3°C). In September, the average low-temperature is 51.3°F (10.7°C).

Humidity

In September, the average relative humidity in Rock Springs is 36%.

Rainfall

In Rock Springs, Wyoming, during September, the rain falls for 7.2 days and regularly aggregates up to 0.63" (16mm) of precipitation. In Rock Springs, Wyoming, during the entire year, the rain falls for 93.5 days and collects up to 10.31" (262mm) of precipitation.

Snowfall

Months with snowfall in Rock Springs are January through June, September through December. September is the first month it typically snows in Rock Springs. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow. In Rock Springs, Wyoming, during the entire year, snow falls for 75.5 days and aggregates up to 30.16" (766mm) of snow.

Daylight

In Rock Springs, the average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:43 am and sunset at 7:50 pm. On the last day of September, sunrise is at 7:12 am and sunset at 7:00 pm MDT.

Sunshine

In Rock Springs, the average sunshine in September is 10.7h.

UV index

The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the temperature in September in Rock Springs?

In September, the average high-temperature is 70.3°F (21.3°C), and the average low-temperature is 51.3°F (10.7°C).

What is the average humidity in September in Rock Springs?

The average relative humidity in September in Rock Springs, Wyoming, is 36%.

How much does it rain in Rock Springs in September?

In September, in Rock Springs, Wyoming, the rain falls for 7.2 days. Throughout September, 0.63" (16mm) of precipitation is accumulated.

When does it start snowing in Rock Springs?

September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow.

What is the average length of the day in September in Rock Springs?

The average day length in September is 12h and 28min.

What time are sunrise and sunset in September in Rock Springs?

On the first day of September, sunrise is at 6:43 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:12 am and sunset at 7:00 pm MDT.

How many hours of sunshine does Rock Springs have in September?

The average sunshine duration in September in Rock Springs is 10.7h.

What is the UV index reading in September in Rock Springs?

In Rock Springs, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate vulnerability from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Rock Springs, WY

Average temperature in September - Rock Springs, WY
  • Average high temperature in September: 70.3°F

The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is December (25.7°F).

  • Average low temperature in September: 51.3°F

The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is January (10.8°F).

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Average pressure in September
Rock Springs, WY

Average pressure in September - Rock Springs, WY
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is January (30.28"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).

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Average wind speed in September
Rock Springs, WY

Average wind speed in September - Rock Springs, WY
  • Average wind speed in September: 9.4mph

The windiest month (with the highest average wind speed) is April (12.2mph).
The calmest month (with the lowest average wind speed) is August (8.7mph).

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Average humidity in September
Rock Springs, WY

Average humidity in September - Rock Springs, WY
  • Average humidity in September: 36%

The month with the highest relative humidity is January (84%).
The months with the lowest relative humidity are July and August (31%).

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Average rainfall in September
Rock Springs, WY

Average rainfall in September - Rock Springs, WY
  • Average rainfall in September: 0.63"

The wettest month (with the highest rainfall) is May (1.5").
The driest month (with the least rainfall) is July (0.47").

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Average rainfall days in September
Rock Springs, WY

Average rainfall days in September - Rock Springs, WY
  • Average rainfall days in September: 7.2 days

The month with the highest number of rainy days is May (13.8 days).
The month with the least rainy days is December (4.7 days).

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Average snowfall in September
Rock Springs, WY

Average snowfall in September - Rock Springs, WY
  • Average snowfall in September: 0.04"

The month with the highest snowfall is March (6.14").
The months with the least snowfall are July and August (0").

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Average snowfall days in September
Rock Springs, WY

Average snowfall days in September - Rock Springs, WY
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is December (13.5 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in September /
Average sunshine in September
Rock Springs, WY

Average daylight in September / Average sunshine in September - Rock Springs, WY
  • Average daylight in September: 12h and 28min

The month with the longest days is June (Average daylight: 15h and 8min).
The month with the shortest days is December (Average daylight: 9h and 13min).

  • Average sunshine in September: 10h and 42min

The months with the most sunshine are July and August (Average sunshine: 11h and 48min).
The months with the least sunshine are January and December (Average sunshine: 5h and 54min).

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Average sunshine days in September
Rock Springs, WY

Average sunshine days in September - Rock Springs, WY
  • Average sunshine days in September: 19.8 days

The month with the most sunshine days is September (19.8 days).
The month with the least sunshine days is April (11.5 days).

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Average UV index in September
Rock Springs, WY

Average UV index in September - Rock Springs, WY
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

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Average cloud cover in September
Rock Springs, WY

Average cloud cover in September - Rock Springs, WY
  • Average cloud cover in September: 14

The month with the most cloud cover is February (Cloud cover 43).
The month with the least cloud cover is August (Cloud cover 13).

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Average visibility in September
Rock Springs, WY

Average visibility in September - Rock Springs, WY
  • Average visibility in September: 6mi

The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).

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