September weather forecast
Green River, WY

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Weather in September

September indicates the onset of autumn in Green River, Wyoming, characterised by a significant drop in temperatures. The weather becomes noticeably milder from the preceding August, as maximum temperatures fall to 70.3°F (21.3°C) and minimum to 51.3°F (10.7°C). September sets itself apart with the cloud cover percentage rising to 14% after a comparatively clear summer sky. The transition from harsh summer days to the softer, more serene autumn weather is clearly observable in this month. September in Green River brings a sense of tranquillity, as the landscape bathed in soft sunlight begins its preparations for the approaching winter.

Temperature

The arrival of September in Green River, Wyoming, corresponds with a temperature reduction, down from August's warm 79.3°F (26.3°C) to an agreeable 70.3°F (21.3°C). Green River, in the month of September, anticipates a consistent average low-temperature of 51.3°F (10.7°C).

Humidity

In Green River, the average relative humidity in September is 36%.

Rainfall

In Green River, during September, the rain falls for 7.2 days and regularly aggregates up to 0.63" (16mm) of precipitation. Throughout the year, in Green River, there are 93.5 rainfall days, and 10.31" (262mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through June, September through December. September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, in Green River, there are 75.5 snowfall days, and 30.16" (766mm) of snow is accumulated.

Daylight

In Green River, Wyoming, the average length of the day in September is 12h and 28min.
On the first day of the month, sunrise is at 6:44 am and sunset at 7:50 pm. On the last day of September, in Green River, sunrise is at 7:14 am and sunset at 7:00 pm MDT.

Sunshine

The average sunshine in September in Green River, Wyoming, is 10.7h.

UV index

In September, the average daily maximum UV index in Green River is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for average individuals.
Note: A maximum daily UV index of 4 during September morphs into the following directions:
Exercise caution. Those with pale skin may experience burns in less than half an hour. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation. Remember to consider! The UV radiation from the Sun can be intensified nearly twice by the reflection of snow.
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Frequently asked questions

What are the temperatures in Green River in September?

September temperatures in Green River, Wyoming, vary between a high-temperature of 70.3°F (21.3°C) and a low-temperature of 51.3°F (10.7°C).

What is the average humidity in September in Green River?

The average relative humidity in September in Green River, Wyoming, is 36%.

How many days does it rain in September in Green River?

In Green River, Wyoming, in September, during 7.2 rainfall days, 0.63" (16mm) of precipitation is typically accumulated.

When does it start to snow in Green River?

September is the first month it typically snows in Green River, Wyoming. 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 Green River?

In Green River, Wyoming, the average day length in September is 12h and 28min.

When are sunrise and sunset in September in Green River?

On the first day of September, sunrise is at 6:44 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 7:00 pm MDT.

How many hours of sunshine does Green River have in September?

In September, the average sunshine duration is 10.7h.

What is the UV index intensity in September in Green River?

In Green River, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium hazard to health from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Green River, WY

Average temperature in September - Green River, 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
Green River, WY

Average pressure in September - Green River, 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
Green River, WY

Average wind speed in September - Green River, 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
Green River, WY

Average humidity in September - Green River, 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
Green River, WY

Average rainfall in September - Green River, 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
Green River, WY

Average rainfall days in September - Green River, 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
Green River, WY

Average snowfall in September - Green River, 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
Green River, WY

Average snowfall days in September - Green River, 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
Green River, WY

Average daylight in September / Average sunshine in September - Green River, 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 12min).

  • Average sunshine in September: 10h and 4min

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
Green River, WY

Average sunshine days in September - Green River, 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
Green River, WY

Average UV index in September - Green River, 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
Green River, WY

Average cloud cover in September - Green River, 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
Green River, WY

Average visibility in September - Green River, 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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Green River, Wyoming, USA

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