September weather forecastSwan, IA
September
Weather in September
September, the first month of the autumn in Swan, is also a moderately hot month, with an average temperature fluctuating between 56.1°F (13.4°C) and 75.7°F (24.3°C).Temperature
As September begins, there is a minor decrease in the average high-temperature, softly falling from 81.3°F (27.4°C) in August to a still moderately hot 75.7°F (24.3°C). The nighttime temperature dips to a refreshing 56.1°F (13.4°C) on average during September.Humidity
In Swan, the average relative humidity in September is 76%.Rainfall
In September, in Swan, the rain falls for 9.5 days. Throughout September, 1.42" (36mm) of precipitation is accumulated. Throughout the year, there are 109.9 rainfall days, and 12.72" (323mm) of precipitation is accumulated.Snowfall
May through September are months without snowfall.Daylight
In Swan, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:40 am and sunset at 7:45 pm. On the last day of the month, sunrise is at 7:09 am and sunset at 6:56 pm CDT.
Sunshine
In Swan, the average sunshine in September is 9.4h.UV index
In Swan, Iowa, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.Note: In September, a regular UV index of 4 translates into these guidelines:
Prioritize safety - Recommendations to avert sunburn are shared. The Sun's radiation is especially intense around midday; try to stay in shade during this period. 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.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Swan, IA
- Average high temperature in September: 75.7°F
The warmest month (with the highest average high temperature) is July (82.9°F).
The month with the lowest average high temperature is January (28.4°F).
- Average low temperature in September: 56.1°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (15.1°F).
Average pressure in September
Swan, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Swan, IA
- Average wind speed in September: 7.9mph
The windiest months (with the highest average wind speed) are January and April (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.8mph).
Average humidity in September
Swan, IA
- Average humidity in September: 76%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Swan, IA
- Average rainfall in September: 1.42"
The wettest month (with the highest rainfall) is May (2.28").
The driest months (with the least rainfall) are January and December (0.39").
Average rainfall days in September
Swan, IA
- Average rainfall days in September: 9.5 days
The month with the highest number of rainy days is May (15.3 days).
The month with the least rainy days is February (3.3 days).
Average snowfall in September
Swan, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Swan, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Swan, 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 24min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Swan, IA
- Average sunshine days in September: 17.9 days
The month with the most sunshine days is December (22.7 days).
The month with the least sunshine days is June (10.9 days).
Average UV index in September
Swan, 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
Swan, 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, August and September (Cloud cover 29).
Average visibility in September
Swan, IA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
