September weather forecastIowa City, IA
September
Weather in September
September signals the arrival of fall in Iowa City. The highest temperature drops to a comfortable 75.2°F (24°C) while the lower end stays comfortably above freezing. Emerald green leaves slowly acquire warm, russet hues as daylight hours begin to shorten. The cityscape transforms into a canvas of vibrant fall colors, making it an attractive period for sightseers.Temperature
The start of September signals a gentle decrease in the average high-temperature, transitioning from a warm 80.6°F (27°C) in August to a still moderately hot 75.2°F (24°C). Iowa City, in September, witnesses an average low-temperature of 55.8°F (13.2°C).Humidity
The average relative humidity in September is 76%.Rainfall
In Iowa City, Iowa, in September, during 12 rainfall days, 2.44" (62mm) of precipitation is typically accumulated. Throughout the year, there are 140.4 rainfall days, and 29.57" (751mm) of precipitation is accumulated.Snowfall
May through September are months without snowfall.Daylight
The average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:38 pm. On the last day of September, sunrise is at 7:02 am and sunset at 6:49 pm CDT.
Sunshine
In September, the average sunshine is 9.3h.UV index
The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: An average maximum UV index of 4 in September leads to these recommendations:
Exercise prevention - Protecting skin and eyes from harm is required. Avoid the Sun's strongest UV rays by seeking shade and limiting exposure during midday. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Iowa City, IA
- Average high temperature in September: 75.2°F
The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (27.3°F).
- Average low temperature in September: 55.8°F
The month with the highest average low temperature is July (64.6°F).
The coldest month (with the lowest average low temperature) is January (15.3°F).
Average pressure in September
Iowa City, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in September
Iowa City, IA
- Average wind speed in September: 8mph
The windiest month (with the highest average wind speed) is April (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (6.9mph).
Average humidity in September
Iowa City, IA
- Average humidity in September: 76%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Iowa City, IA
- Average rainfall in September: 2.44"
The wettest month (with the highest rainfall) is May (4.69").
The driest months (with the least rainfall) are January and February (1.34").
Average rainfall days in September
Iowa City, IA
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (18.4 days).
The month with the least rainy days is February (5 days).
Average snowfall in September
Iowa City, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.28").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Iowa City, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (10.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Iowa City, IA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 12min).
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 0min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Iowa City, IA
- Average sunshine days in September: 17.1 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is May (10 days).
Average UV index in September
Iowa City, IA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Iowa City, IA
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Iowa City, IA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
