September weather forecast and climate
Denver, CO

The colorful sky above the sunlit Denver city, Colorado in autumn
The colorful sky above the sunlit Denver city, Colorado in autumn
September, the first month of the autumn, in Denver, is still a warm month, with average temperature ranging between max 76.6°F (24.8°C) and min 51.4°F (10.8°C).

Temperature

In September, the average high-temperature slightly decreases, from 83.1°F (28.4°C) in August, to a still warm 76.6°F (24.8°C). In September, in Denver, the average low-temperature is 51.4°F (10.8°C).

Humidity

In September, the average relative humidity in Denver, Colorado, is 43%.

Rainfall

In Denver, it is raining for 9.5 days, with typically 0.71" (18mm) of accumulated precipitation. Throughout the year, there are 119.5 rainfall days, and 12.95" (329mm) of precipitation is accumulated.

Snowfall

June through September are months without snowfall.

Daylight

In September, the average length of the day in Denver is 12.4h.

Sunshine

In September, the average sunshine is 11.1h.

UV index

The average daily maximum UV index is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from the exposure to the Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.

What is the temperature in September in Denver?

In Denver, in September, the average high-temperature is 76.6°F (24.8°C), and the average low-temperature is 51.4°F (10.8°C).

What is the average humidity in September in Denver?

In September, the average relative humidity in Denver, Colorado, is 43%.

How many days does it rain in September in Denver?

In Denver, Colorado, in September, it is raining for 9.5 days, with typically 0.71" (18mm) of accumulated precipitation.

Does it snow in Denver in September?

In Denver, in September, it doesn't snow. In October, it regularly snows.

When it does not snow in Denver?

In Denver snow does not fall in June through September.

How many hours of daylight does Denver have in September?

In September, the average length of the day is 12.4h.

How many hours of sunshine does Denver have in September?

In Denver, the average sunshine in September is 11.1h.

What is the UV index reading in September in Denver?

In September, the average daily maximum UV index in Denver is 5. A UV Index value of 3 to 5 symbolizes a medium hazard to health from the exposure to the Sun's UV radiation.
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"

The month with the highest atmospheric pressure is January (30.14").
The month with the lowest atmospheric pressure is April (29.91").

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").
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).
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: 12.4h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in September: 11.1h

Months with the most sunshine are June, July and August (Average sunshine: 11.8h).
The month with the least sunshine is February (Average sunshine: 6.9h).

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

Months with the highest UV index are June and July (UV index 6).
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

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).