September weather forecastDonnellson, IA
September
Weather in September
September, the first month of the autumn in Donnellson, is still a warm month, with temperature in the range of an average high of 77°F (25°C) and an average low of 57.4°F (14.1°C).Temperature
Donnellson in September undergoes a slight reduction in the average high-temperature, shifting from August's 82.6°F (28.1°C) to a still warm 77°F (25°C). In the month of September, the nighttime temperature in Donnellson dips to a steady average of 57.4°F (14.1°C).Humidity
The average relative humidity in September in Donnellson, Iowa, is 75%.Rainfall
In Donnellson, in September, during 12 rainfall days, 2.28" (58mm) of precipitation is typically accumulated. In Donnellson, during the entire year, the rain falls for 145.2 days and collects up to 28.98" (736mm) of precipitation.Snowfall
May through September are months without snowfall in Donnellson.Daylight
In September, the average length of the day in Donnellson is 12h and 27min.On the first day of the month, sunrise is at 6:34 am and sunset at 7:37 pm. On the last day of September, in Donnellson, Iowa, sunrise is at 7:02 am and sunset at 6:49 pm CDT.
Sunshine
In September, the average sunshine in Donnellson is 9.5h.UV index
In Donnellson, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for the ordinary person.Note: The UV index of 4 in September translates into these instructions:
Ensure safety - Imperative it is to shield skin and eyes from damage. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Donnellson, IA
- Average high temperature in September: 77°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 (30.2°F).
- Average low temperature in September: 57.4°F
The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).
Average pressure in September
Donnellson, 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 (29.9"Hg).
Average wind speed in September
Donnellson, IA
- Average wind speed in September: 7.7mph
The windiest month (with the highest average wind speed) is January (10.6mph).
The calmest month (with the lowest average wind speed) is July (6.7mph).
Average humidity in September
Donnellson, IA
- Average humidity in September: 75%
The month with the highest relative humidity is July (82%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Donnellson, IA
- Average rainfall in September: 2.28"
The wettest month (with the highest rainfall) is May (4.25").
The driest month (with the least rainfall) is December (1.38").
Average rainfall days in September
Donnellson, IA
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is May (19.2 days).
The month with the least rainy days is February (4.9 days).
Average snowfall in September
Donnellson, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.41").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Donnellson, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.2 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
Donnellson, IA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in September: 9h and 30min
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 12min).
Average sunshine days in September
Donnellson, IA
- Average sunshine days in September: 16.3 days
The month with the most sunshine days is November (18.7 days).
The month with the least sunshine days is May (9.2 days).
Average UV index in September
Donnellson, IA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Donnellson, 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
Donnellson, 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).
