September weather forecastAlton, IA
September
Weather in September
September, the first month of the autumn in Alton, is also a moderately hot month, with an average temperature varying between 54.5°F (12.5°C) and 74.3°F (23.5°C).Temperature
September's arrival subtly correlates with a reduction in the average high-temperature, down from a moderately hot 80.2°F (26.8°C) in August to a still warm 74.3°F (23.5°C). Throughout September nights, Alton experiences a consistent temperature average of 54.5°F (12.5°C).Humidity
The average relative humidity in September is 72%.Rainfall
In Alton, during September, the rain falls for 11.3 days and regularly aggregates up to 2.01" (51mm) of precipitation. Throughout the year, there are 124 rainfall days, and 24.09" (612mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall in Alton, Iowa.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 6:49 am and sunset at 7:58 pm. On the last day of September, sunrise is at 7:21 am and sunset at 7:06 pm CDT.
Sunshine
In Alton, the average sunshine in September is 8.8h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: In September, a regular UV index of 4 translates into these guidelines:
Make use of precautions - It is urged to ward off sun damage. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Alton, IA
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (24.6°F).
- Average low temperature in September: 54.5°F
The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is January (11.3°F).
Average pressure in September
Alton, IA
- Average pressure in September: 29.99"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).
Average wind speed in September
Alton, IA
- Average wind speed in September: 9.3mph
The windiest month (with the highest average wind speed) is April (11.3mph).
The calmest month (with the lowest average wind speed) is July (7.8mph).
Average humidity in September
Alton, IA
- Average humidity in September: 72%
The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is October (67%).
Average rainfall in September
Alton, IA
- Average rainfall in September: 2.01"
The wettest month (with the highest rainfall) is June (3.82").
The driest month (with the least rainfall) is January (0.79").
Average rainfall days in September
Alton, IA
- Average rainfall days in September: 11.3 days
The month with the highest number of rainy days is June (18 days).
The month with the least rainy days is February (2.8 days).
Average snowfall in September
Alton, IA
- Average snowfall in September: 0"
The month with the highest snowfall is February (4.61").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Alton, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (12.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Alton, IA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 8h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Alton, IA
- Average sunshine days in September: 16.5 days
The month with the most sunshine days is November (20.3 days).
The month with the least sunshine days is June (9.3 days).
Average UV index in September
Alton, 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 and December (UV index 1).
Average cloud cover in September
Alton, 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 July (Cloud cover 28).
Average visibility in September
Alton, IA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is January (5mi).
