Denver Weather in September
September offers excellent weather for Denver, Colorado. It is the year's sunniest month. And the days have cooled down from the rest of summer.
This page gives detailed information on the typical September temperature, precipitation, snow, sun, humidity, wind and storms for Denver. The numbers here are historical averages based on climate data gathered in the Denver community of Stapleton.
|80 °F||September average high||27 °C|
|48 °F||September average low||9 °C|
|17 days||80 °F max. or more (27 °C)|
|17 days||50 °F min. or less (10 °C)|
Nearly every day in September warms to over 60 degrees Fahrenheit (16 degrees Celsius) in Denver. The city averages four days this month when the thermometer reaches into the 90s °F (over 32 °C). Temperatures above 100 °F (38 °C) are not expected here during September.
At night, the thermometer dips to 40 °F (7 °C) or below on 4 days. September occasionally has a night of frost.
|1.5 in||total precipitation||38 mm|
|6 days||of rain or snowfall|
Half the time, Denver receives 0.5 to 1.6 inches (14 to 41 mm) of precipitation in September. One in four years has drier weather, while another one in four is wetter.
|0.8 in||total snowfall||2 cm|
|1 day||with new snow|
Most years, Denver receives no snow in September.
|13 days||clear skies|
September is Denver's sunniest month of the year. The sun's rays reach the ground here during 74 percent of daylight hours on average, for a total of 276 hours in the month. Typically on 13 days this month the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in September at Denver lasts for 12 hours and 25 minutes a day on average. The longest day of the month is the 1st with 13 hours and 2 minutes of daylight. By the end of the month, the days have shortened to 11:48 from sunrise to sunset. These durations can vary by a minute or two from year to year.
|50 %||September average humidity|
The relative humidity in Denver during September usually peaks at 69 percent in the morning then drops to 31 percent by early afternoon.
|Local Time||2 am||5 am||8 am||11 am||2 pm||5 pm||8 pm||11 pm|
|8.0 mph||September wind speed average||12.9 kph|
September is less windy than most other months in Denver.
|1 day||rainfall of 0.5 inches (13 mm) or more|
|4 days||with thunderstorms in September|
Every few years, Denver gets an inch (2.5 cm) or more of fresh snow in one day during September.
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.