September weather forecastDes Moines, IA
September
Weather in September
The transition from summer to autumn becomes evident in Des Moines during September. The daylight hours reduce further, and slight dips in temperature make the weather more comfortable. A decrease in humidity coupled with a relatively balanced rain and sunshine duration, ensures an enjoyable outdoor ambiance. September reports an average temperature ranging from 55.9°F (13.3°C) to 75.6°F (24.2°C). As greens turn into oranges and browns, the cityscape offers a picturesque fall sight for its residents and visitors.Temperature
September's arrival subtly correlates with a reduction in the average high-temperature, down from 81.7°F (27.6°C) in August to a still warm 75.6°F (24.2°C). Nighttime temperatures in September average to a moderate 55.9°F (13.3°C).Humidity
The average relative humidity in September 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 is 12h and 28min.On the first day of the month, sunrise is at 6:41 am and sunset at 7:47 pm. On the last day of September, sunrise is at 7:11 am and sunset at 6:57 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for the ordinary person.Note: In September, the UV index of 4 transforms into the following advice:
Preventative actions are necessary - Recommendations to ward off sunburn are given. The Sun's radiation is especially intense around midday; try to stay in shade during this period. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Des Moines, IA
- Average high temperature in September: 75.6°F
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is January (28.2°F).
- Average low temperature in September: 55.9°F
The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (15.1°F).
Average pressure in September
Des Moines, IA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Des Moines, IA
- Average wind speed in September: 8mph
The windiest months (with the highest average wind speed) are January, February, March and April (10.3mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in September
Des Moines, IA
- Average humidity in September: 76%
The 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: 1.73"
The wettest month (with the highest rainfall) is May (2.76").
The driest month (with the least rainfall) is January (0.47").
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: 0"
The month with the highest snowfall is January (2.24").
The months with the least snowfall are June, July, August and September (0").
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).
The 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: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in September: 9h and 18min
The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in September
Des Moines, IA
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is December (22.3 days).
The month with the least sunshine days is June (12.2 days).
Average UV index in September
Des Moines, IA
- Average UV index in September: 4
The 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).
Average cloud cover in September
Des Moines, IA
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 54).
The months with the least cloud cover are July and September (Cloud cover 29).
Average visibility in September
Des Moines, IA
- 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).
