September weather forecastMarshalltown, IA
September
Weather in September
Marshalltown in September sees the arrival of the fall season. The temperatures start to dip gradually, and the rainfall drops to 1.5" (38mm), indicating a shift in weather. The signs of autumn start to occur as the leaves begin to change and the weather starts to cool down. People have ample opportunity to appreciate the outdoors with pleasing weather during the day. Despite the decrease in temperature, the weather is generally mild, ideal for enjoying the beautifully changing landscape.Temperature
The arrival of September in Marshalltown coincides with an average high-temperature of a still warm 74.5°F (23.6°C), indicating a minimal shift from August's 79.2°F (26.2°C). Marshalltown's temperature lowers to a mean of 55.2°F (12.9°C) during the nights in September.Humidity
In Marshalltown, Iowa, the average relative humidity in September is 77%.Rainfall
In September, in Marshalltown, the rain falls for 10.6 days. Throughout September, 1.5" (38mm) of precipitation is accumulated. Throughout the year, there are 118.2 rainfall days, and 16.18" (411mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall in Marshalltown, Iowa.Daylight
The average length of the day in September is 12h and 28min.On the first day of the month, sunrise is at 6:38 am and sunset at 7:44 pm. On the last day of September, in Marshalltown, sunrise is at 7:08 am and sunset at 6:54 pm CDT.
Sunshine
In Marshalltown, the average sunshine in September is 9.3h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: During September, 4 as the daily maximum UV index converts into the following advice:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Marshalltown, IA
- Average high temperature in September: 74.5°F
The warmest month (with the highest average high temperature) is July (80.8°F).
The month with the lowest average high temperature is January (25.7°F).
- Average low temperature in September: 55.2°F
The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (12.7°F).
Average pressure in September
Marshalltown, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Marshalltown, IA
- Average wind speed in September: 8.3mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest months (with the lowest average wind speed) are July and August (7.1mph).
Average humidity in September
Marshalltown, IA
- Average humidity in September: 77%
The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Marshalltown, IA
- Average rainfall in September: 1.5"
The wettest month (with the highest rainfall) is June (2.56").
The driest month (with the least rainfall) is January (0.43").
Average rainfall days in September
Marshalltown, IA
- Average rainfall days in September: 10.6 days
The month with the highest number of rainy days is June (15.7 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in September
Marshalltown, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.93").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Marshalltown, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Marshalltown, 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: 3h and 54min).
Average sunshine days in September
Marshalltown, IA
- Average sunshine days in September: 18 days
The month with the most sunshine days is December (20.6 days).
The month with the least sunshine days is June (12.2 days).
Average UV index in September
Marshalltown, IA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in September
Marshalltown, IA
- Average cloud cover in September: 30
The month with the most cloud cover is January (Cloud cover 57).
The month with the least cloud cover is September (Cloud cover 30).
Average visibility in September
Marshalltown, 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).
