Des Moines
Iowa, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Des Moines, IA

The first month of the autumn, September, is also a moderately hot month in Des Moines, Iowa, with average temperature fluctuating between 75.6°F (24.2°C) and 55.9°F (13.3°C).

Temperature

In Des Moines, the average high-temperature slightly decreases, from 81.7°F (27.6°C) in August, to a still moderately hot 75.6°F (24.2°C). In Des Moines, in September, the average low-temperature is 55.9°F (13.3°C).

Humidity

In September, the average relative humidity is 76%.

Rainfall

In Des Moines, in September, during 10.5 rainfall days, 1.73" (44mm) of precipitation is typically accumulated. In Des Moines, during the entire year, the rain falls for 114.4 days and collects up to 16.38" (416mm) of precipitation.

Snowfall

June through September are months without snowfall.

Daylight

In September, the average length of the day in Des Moines is 12.5h.

Sunshine

In Des Moines, Iowa, the average sunshine in September is 9.3h.

UV index

In September, the average daily maximum UV index in Des Moines is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from unprotected exposure to the Sun's UV rays for the average person.
Note: The daily maximum UV index of 4 interpret into the following advice:
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. 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.

What is the temperature in September in Des Moines?

In September, in Des Moines, Iowa, the average high-temperature is 75.6°F (24.2°C), and the average low-temperature is 55.9°F (13.3°C).

What is the average humidity in September in Des Moines?

In Des Moines, the average relative humidity in September is 76%.

How many days does it rain in September in Des Moines?

In Des Moines, Iowa, in September, during 10.5 rainfall days, 1.73" (44mm) of precipitation is typically accumulated.

Does it snow in Des Moines in September?

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

When it does not snow in Des Moines?

In Des Moines, Iowa, snow does not fall in June through September.

What is the average length of the day in September in Des Moines?

In Des Moines, the average length of the day in September is 12.5h.

How long on average sun shines in September in Des Moines?

In September, the average sunshine in Des Moines, Iowa, is 9.3h.

What is the UV index reading in September in Des Moines?

In September, the average daily maximum UV index in Des Moines, Iowa, is 4. A UV Index estimate of 3 to 5 represents a medium health risk from the exposure to the Sun's UV rays.
Average temperature in September - Des Moines, IA
  • Average high temperature in September: 24.2°C

The warmest month (with the highest average high temperature) is July (28.4°C).
The month with the lowest average high temperature is January (-2.1°C).

  • Average low temperature in September: 13.3°C

The month with the highest average low temperature is July (18.6°C).
The coldest month (with the lowest average low temperature) is January (-9.4°C).

Average humidity in September - Des Moines, IA
  • Average humidity in September: 76%

Months with the highest relative humidity are January and June (82%).
The month with the lowest relative humidity is October (70%).

Average rainfall in September - Des Moines, IA
  • Average rainfall in September: 44mm

The wettest month (with the highest rainfall) is May (70mm).
The driest month (with the least rainfall) is January (12mm).

Average rainfall days in September - Des Moines, IA
  • Average rainfall days in September: 10.5 days

The month with the highest number of rainy days is June (15.9 days).
The month with the least rainy days is February (3 days).

Average snowfall in September - Des Moines, IA
  • Average snowfall in September: 0mm

The month with the highest snowfall is January (57mm).
Months with the least snowfall are June, July, August and September (0mm).

Average snowfall days in September - Des Moines, IA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (8.7 days).
Months with the least snowfall days are June, July, August and September (0 days).

Average daylight in September / Average sunshine in September - Des Moines, IA
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.2h).
The month with the shortest days is December (Average daylight: 9.2h).

  • Average sunshine in September: 9.3h

The month with the most sunshine is July (Average sunshine: 10.3h).
The month with the least sunshine is January (Average sunshine: 4.3h).

Average UV index in September - Des Moines, IA
  • Average UV index in September: 4

Months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).