Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The average high-temperature decreases in September, shifting from a moderately hot 77.5°F (25.3°C) in August to a pleasant 68.5°F (20.3°C). September nights are characterized by a significant departure from the daytime highs, dropping to an average temperature of 45°F (7.2°C).Humidity
The average relative humidity in September is 44%.Rainfall
In Altamont, in September, it is raining for 8 days, with typically 0.71" (18mm) of accumulated precipitation. In Altamont, during the entire year, the rain falls for 94.2 days and collects up to 11.5" (292mm) of precipitation.Snowfall
January through June, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 1.1 snowfall days, it receives 0.91" (23mm) of snow. Throughout the year, there are 99.3 snowfall days, and 56.22" (1428mm) of snow is accumulated.Daylight
In Altamont, the average length of the day in September is 12h and 27min.On the first day of the month, sunrise is at 6:50 am and sunset at 7:55 pm. On the last day of September, sunrise is at 7:19 am and sunset at 7:06 pm MDT.
Sunshine
In Altamont, the average sunshine in September is 10.3h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the ordinary person.Note: An average maximum UV index of 4 in September leads to these recommendations:
Take precautions - Protection against sun damage is advised. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. To best shield against UV radiation, choose sun-safe garments and dependable sunglasses. Be watchful! The reflection of snow can enhance the intensity of the Sun's UV radiation nearly double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September in Altamont?
How many days does it rain in September?
When does it start to snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Altamont, WY
- Average high temperature in September: 68.5°F
The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is December (26.4°F).
- Average low temperature in September: 45°F
The month with the highest average low temperature is July (51.6°F).
The coldest month (with the lowest average low temperature) is January (10.8°F).
Average pressure in September
Altamont, WY
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.29"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Altamont, WY
- Average wind speed in September: 7.3mph
The windiest month (with the highest average wind speed) is April (8.2mph).
The calmest month (with the lowest average wind speed) is July (6.7mph).
Average humidity in September
Altamont, WY
- Average humidity in September: 44%
The months with the highest relative humidity are January and February (87%).
The month with the lowest relative humidity is August (39%).
Average rainfall in September
Altamont, WY
- Average rainfall in September: 0.71"
The wettest months (with the highest rainfall) are April and May (1.38").
The driest month (with the least rainfall) is August (0.51").
Average rainfall days in September
Altamont, WY
- Average rainfall days in September: 8 days
The month with the highest number of rainy days is May (11.9 days).
The month with the least rainy days is February (5.5 days).
Average snowfall in September
Altamont, WY
- Average snowfall in September: 0.91"
The month with the highest snowfall is March (10").
The months with the least snowfall are July and August (0").
Average snowfall days in September
Altamont, WY
- Average snowfall days in September: 1.1 days
The month with the highest number of snowfall days is February (16.3 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in September /
Average sunshine in September
Altamont, 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 2min
The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 48min).
Average sunshine days in September
Altamont, WY
- Average sunshine days in September: 17 days
The month with the most sunshine days is June (19.5 days).
The month with the least sunshine days is April (10.8 days).
Average UV index in September
Altamont, WY
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are November and December (UV index 1).
Average cloud cover in September
Altamont, WY
- Average cloud cover in September: 13
The month with the most cloud cover is February (Cloud cover 45).
The month with the least cloud cover is August (Cloud cover 10).
Average visibility in September
Altamont, WY
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and February (4mi).
Altamont, Wyoming, USA
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