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 also a moderately hot month, with average temperature ranging between max 76.6°F (24.8°C) and min 51.4°F (10.8°C).

Temperature

In Denver, Colorado, the average high-temperature marginally drops, from a warm 83.1°F (28.4°C) in August, to a still moderately hot 76.6°F (24.8°C). In Denver, the average low-temperature is 51.4°F (10.8°C).

Humidity

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, Colorado, during the entire year, the rain falls for 119.5 days and collects up to 12.95" (329mm) of precipitation.

Snowfall

In Denver snow does not fall in June through September.

Daylight

The average length of the day in Denver is 12.4h.

Sunshine

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

UV index

The average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from the exposure to the Sun's UV radiation for average individuals.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions - Protection against the skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the temperature in September in Denver?

In Denver, Colorado, 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?

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

How much does it rain in Denver in September?

In Denver, in September, during 9.5 rainfall days, 0.71" (18mm) of precipitation is typically accumulated.

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 in Denver, Colorado, is 12.4h.

How many hours of sunshine does Denver have in September?

The average sunshine in September in Denver, Colorado, is 11.1h.

How high is the UV index in September in Denver?

In September, the average daily maximum UV index in Denver, Colorado, is 5. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from the exposure to the Sun's UV rays.
Average temperature in September - Denver, CO
  • Average high temperature in September: 24.8°C

The warmest month (with the highest average high temperature) is July (29.1°C).
The month with the lowest average high temperature is December (4.4°C).

  • Average low temperature in September: 10.8°C

The month with the highest average low temperature is July (15.1°C).
The coldest month (with the lowest average low temperature) is December (-6.3°C).

Average pressure in September - Denver, CO
  • Average pressure in September: 1016.3mbar

The month with the highest atmospheric pressure is January (1020.7mbar).
The month with the lowest atmospheric pressure is April (1012.9mbar).

Average wind speed in September - Denver, CO
  • Average wind speed in September: 9.2km/h

The windiest month (with the highest average wind speed) is April (10.6km/h).
The calmest months (with the lowest average wind speed) are August and September (9.2km/h).

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: 18mm

The wettest month (with the highest rainfall) is May (60mm).
The driest months (with the least rainfall) are January and December (10mm).

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: 0mm

The month with the highest snowfall is March (159mm).
Months with the least snowfall are June, July, August and September (0mm).

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: 10km

Months with the highest visibility are January, March, April, May, June, July, August, September, October, November and December (10km).
The month with the lowest visibility is February (9km).