September weather forecastFort Collins, CO
September
Weather in September
September in Fort Collins brings a noticeable drop in temperature, to a mild 74.5°F (23.6°C), indicating the onset of the fall season. This month marks the transition from the peak summer heat to a much cooler autumn climate. The fall foliage, coupled with cool temperatures, makes the city a picturesque destination. With dryer weather and lesser clouds, it's an ideal time for those seeking to enjoy the outdoors.Temperature
The arrival of September is marked by a minor reduction in average high-temperature, sliding from a moderately hot 81.5°F (27.5°C) in August to a still warm 74.5°F (23.6°C). In Fort Collins, the average temperature during the nights of September marks a significant drop from the daily high, settling at a frosty 49.3°F (9.6°C).Humidity
June, August and September, with an average relative humidity of 45%, are the least humid months in Fort Collins.Rainfall
In Fort Collins, in September, during 6.3 rainfall days, 0.55" (14mm) of precipitation is typically accumulated. Throughout the year, in Fort Collins, there are 73.4 rainfall days, and 7.64" (194mm) of precipitation is accumulated.Snowfall
In Fort Collins, snow does not fall in June through September.Daylight
The average length of the day in September is 12h and 27min.On the first day of September in Fort Collins, sunrise is at 6:28 am and sunset at 7:31 pm. On the last day of the month, sunrise is at 6:56 am and sunset at 6:43 pm MDT.
Sunshine
In Fort Collins, Colorado, the average sunshine in September is 11h.UV index
In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for ordinary individuals.Note: The UV index of 4 in September translates into these instructions:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Fort Collins, CO
- Average high temperature in September: 74.5°F
The warmest month (with the highest average high temperature) is July (82.9°F).
The month with the lowest average high temperature is December (36.1°F).
- Average low temperature in September: 49.3°F
The month with the highest average low temperature is July (56.8°F).
The coldest month (with the lowest average low temperature) is December (18.7°F).
Average pressure in September
Fort Collins, CO
- Average pressure in September: 29.99"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Fort Collins, CO
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is August (5.6mph).
Average humidity in September
Fort Collins, CO
- Average humidity in September: 45%
The month with the highest relative humidity is February (67%).
The months with the lowest relative humidity are June, August and September (45%).
Average rainfall in September
Fort Collins, CO
- Average rainfall in September: 0.55"
The wettest month (with the highest rainfall) is May (1.5").
The driest month (with the least rainfall) is January (0.12").
Average rainfall days in September
Fort Collins, CO
- Average rainfall days in September: 6.3 days
The month with the highest number of rainy days is July (14.6 days).
The month with the least rainy days is January (1.2 days).
Average snowfall in September
Fort Collins, CO
- Average snowfall in September: 0"
The month with the highest snowfall is April (3.27").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Fort Collins, CO
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Fort Collins, CO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in September: 11h and 0min
The month with the most sunshine is June (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 6h and 42min).
Average sunshine days in September
Fort Collins, CO
- Average sunshine days in September: 21.7 days
The months with the most sunshine days are January and December (27.5 days).
The month with the least sunshine days is July (14.9 days).
Average UV index in September
Fort Collins, CO
- 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, November and December (UV index 2).
Average cloud cover in September
Fort Collins, CO
- Average cloud cover in September: 16
The months with the most cloud cover are February, April and May (Cloud cover 27).
The month with the least cloud cover is September (Cloud cover 16).
Average visibility in September
Fort Collins, CO
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
