September weather forecastDenver, CO
September
Weather in September
As Denver transitions into September, the city experiences a gradual change in its weather outlook. No longer peaking at summer highs, the temperature in September moderately decreases with an average high placed at 76.6°F (24.8°C). Signalling the initial hints of fall, the city experiences shorter daylight hours and diminishing rainfall with a drop to 0.71" (18mm) from the preceding month. A unique weather scenario takes shape in September as it’s the first month of the year with no recorded snowfall. Therefore, Denver's September weather notably moves from the summer heat towards milder, comfortable days of early fall.
Temperature
During the shift to September, Denver records a mild decrease in average high-temperature, moving from 83.1°F (28.4°C) in August to a still warm 76.6°F (24.8°C). The September nights bear witness to a significant drop from the daytime highs, settling at an average temperature of 51.4°F (10.8°C).Humidity
In September, the average relative humidity in Denver is 43%.Rainfall
In Denver, during September, the rain falls for 9.5 days and regularly aggregates up to 0.71" (18mm) of precipitation. In Denver, during the entire year, the rain falls for 119.5 days and collects up to 12.95" (329mm) of precipitation.Snowfall
June through September are months without snowfall in Denver.Daylight
The average length of the day in September in Denver is 12h and 26min.On the first day of September in Denver, sunrise is at 6:28 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:43 pm MDT.
Sunshine
In Denver, the average sunshine in September is 11.1h.UV index
In September, the average daily maximum UV index in Denver is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: In September, a daily maximum UV index of 5 leads to the following instructions:
Act with care - The need to guard against sun damage is communicated. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. To cut down UV radiation exposure by about half, sport a wide-brim hat. Forewarned is forearmed! The Sun's UV radiation can be almost doubled in intensity by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Denver, CO
- Average high temperature in September: 76.6°F
The warmest month (with the highest average high temperature) is July (84.4°F).
The month with the lowest average high temperature is December (39.9°F).
- Average low temperature in September: 51.4°F
The month with the highest average low temperature is July (59.2°F).
The coldest month (with the lowest average low temperature) is December (20.7°F).
Average pressure in September
Denver, CO
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is April (29.91"Hg).
Average wind speed in September
Denver, CO
- Average wind speed in September: 5.7mph
The windiest month (with the highest average wind speed) is April (6.6mph).
The calmest months (with the lowest average wind speed) are August and September (5.7mph).
Average humidity in September
Denver, CO
- Average humidity in September: 43%
The month with the highest relative humidity is February (66%).
The month with the lowest relative humidity is June (41%).
Average rainfall in September
Denver, CO
- Average rainfall in September: 0.71"
The wettest month (with the highest rainfall) is May (2.36").
The driest months (with the least rainfall) are January and December (0.39").
Average rainfall days in September
Denver, CO
- Average rainfall days in September: 9.5 days
The month with the highest number of rainy days is July (18.4 days).
The month with the least rainy days is January (3.7 days).
Average snowfall in September
Denver, CO
- Average snowfall in September: 0"
The month with the highest snowfall is March (6.26").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Denver, CO
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (9.3 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Denver, CO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 11h and 6min
The months with the most sunshine are June, July and August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 6h and 54min).
Average sunshine days in September
Denver, CO
- Average sunshine days in September: 14.9 days
The month with the most sunshine days is November (23 days).
The month with the least sunshine days is July (5.6 days).
Average UV index in September
Denver, CO
- Average UV index in September: 5
The months with the highest UV index are June and 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
Denver, CO
- Average cloud cover in September: 15
The month with the most cloud cover is April (Cloud cover 26).
The month with the least cloud cover is September (Cloud cover 15).
Average visibility in September
Denver, 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).
