September weather forecastBoulder, WY
September
Weather in September
Boulder transitions into autumn in September, carrying with it a drop in temperatures. A prominent decrease in high temperatures to an average of 67.3°F (19.6°C) marks the transition from summer. The changing weather is marked by a slight uptick in rainfall by 0.79" (20mm). The shifting seasons present a canvas of colors, adding aesthetic beauty to the town's landscape. Despite the moderate winds, the month promises a pleasant environment for various outdoor activities like fishing and hiking.Temperature
In Boulder, the beginning of September is marked by a lowered average high-temperature, shifting from August's warm 76.6°F (24.8°C) to a refreshing 67.3°F (19.6°C). Throughout September, an average nighttime temperature of 46.9°F (8.3°C) is experienced.Humidity
In Boulder, Wyoming, the average relative humidity in September is 40%.Rainfall
In September, in Boulder, the rain falls for 7.2 days. Throughout September, 0.79" (20mm) of precipitation is accumulated. Throughout the year, in Boulder, Wyoming, there are 102.6 rainfall days, and 10.75" (273mm) of precipitation is accumulated.Snowfall
January through June, September through December are months with snowfall in Boulder, Wyoming. September is the first month it typically snows. Throughout September, in the average 0.6 snowfall days, it receives 0.31" (8mm) of snow. Throughout the year, there are 86.8 snowfall days, and 41.77" (1061mm) of snow is accumulated.Daylight
In September, the average length of the day in Boulder, Wyoming, is 12h and 28min.On the first day of September in Boulder, sunrise is at 6:44 am and sunset at 7:52 pm. On the last day of the month, sunrise is at 7:15 am and sunset at 7:01 pm MDT.
Sunshine
In September, the average sunshine is 10.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: A maximum daily UV index of 4 during September morphs into the following directions:
Preventative actions are necessary - Recommendations to ward off sunburn are given. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Boulder, WY
- Average high temperature in September: 67.3°F
The warmest month (with the highest average high temperature) is July (78.4°F).
The month with the lowest average high temperature is December (23.9°F).
- Average low temperature in September: 46.9°F
The month with the highest average low temperature is July (55.2°F).
The coldest month (with the lowest average low temperature) is January (5.4°F).
Average pressure in September
Boulder, WY
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.27"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Boulder, WY
- Average wind speed in September: 6.6mph
The windiest month (with the highest average wind speed) is June (8.1mph).
The calmest month (with the lowest average wind speed) is December (5.8mph).
Average humidity in September
Boulder, WY
- Average humidity in September: 40%
The month with the highest relative humidity is February (86%).
The month with the lowest relative humidity is August (34%).
Average rainfall in September
Boulder, WY
- Average rainfall in September: 0.79"
The wettest month (with the highest rainfall) is May (1.73").
The driest month (with the least rainfall) is August (0.51").
Average rainfall days in September
Boulder, WY
- Average rainfall days in September: 7.2 days
The month with the highest number of rainy days is May (15.2 days).
The month with the least rainy days is January (5.5 days).
Average snowfall in September
Boulder, WY
- Average snowfall in September: 0.31"
The month with the highest snowfall is February (7.32").
The months with the least snowfall are July and August (0").
Average snowfall days in September
Boulder, WY
- Average snowfall days in September: 0.6 days
The month with the highest number of snowfall days is March (15.7 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in September /
Average sunshine in September
Boulder, WY
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 10h and 42min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 6h and 18min).
Average sunshine days in September
Boulder, WY
- Average sunshine days in September: 18.5 days
The month with the most sunshine days is January (19.8 days).
The month with the least sunshine days is May (9.7 days).
Average UV index in September
Boulder, 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).
Average cloud cover in September
Boulder, WY
- Average cloud cover in September: 13
The month with the most cloud cover is February (Cloud cover 39).
The month with the least cloud cover is August (Cloud cover 11).
Average visibility in September
Boulder, 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).
