September weather forecastGrand River, IA
September
Weather in September
The first month of the autumn, September, is still a warm month in Grand River, Iowa, with an average temperature ranging between max 76.1°F (24.5°C) and min 56.3°F (13.5°C).Temperature
September signifies a gentle decline in Grand River's average high-temperature, easing from a moderately hot 81.9°F (27.7°C) in August to a still warm 76.1°F (24.5°C). Throughout September, Grand River experiences a low-temperature average of 56.3°F (13.5°C).Humidity
In Grand River, the average relative humidity in September is 77%.Rainfall
In Grand River, in September, it is raining for 11.5 days, with typically 2.24" (57mm) of accumulated precipitation. In Grand River, during the entire year, the rain falls for 132.4 days and collects up to 20.24" (514mm) of precipitation.Snowfall
In Grand River, Iowa, snow does not fall in June through September.Daylight
The average length of the day in September is 12h and 27min.On the first day of the month, sunrise is at 6:43 am and sunset at 7:47 pm. On the last day of September, sunrise is at 7:12 am and sunset at 6:58 pm CDT.
Sunshine
In Grand River, the average sunshine in September is 9.4h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV rays for average individuals.Note: The daily high UV index of 4 in September translates into this advice:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. Being exposed to the midday Sun can have harmful effects due to strong UV radiation; always take precautions. 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
Grand River, IA
- Average high temperature in September: 76.1°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is January (30.6°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (16.9°F).
Average pressure in September
Grand River, IA
- Average pressure in September: 30.01"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
Grand River, IA
- Average wind speed in September: 7.9mph
The windiest months (with the highest average wind speed) are January, February and March (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.9mph).
Average humidity in September
Grand River, IA
- Average humidity in September: 77%
The month with the highest relative humidity is June (83%).
The month with the lowest relative humidity is October (72%).
Average rainfall in September
Grand River, IA
- Average rainfall in September: 2.24"
The wettest month (with the highest rainfall) is June (3.43").
The driest months (with the least rainfall) are January and December (0.67").
Average rainfall days in September
Grand River, IA
- Average rainfall days in September: 11.5 days
The month with the highest number of rainy days is June (17.3 days).
The month with the least rainy days is January (4.8 days).
Average snowfall in September
Grand River, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.72").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Grand River, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.6 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Grand River, 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 18min).
- Average sunshine in September: 9h and 24min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).
Average sunshine days in September
Grand River, IA
- Average sunshine days in September: 16 days
The month with the most sunshine days is December (20.3 days).
The month with the least sunshine days is June (8.9 days).
Average UV index in September
Grand River, 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
Grand River, IA
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 51).
The month with the least cloud cover is July (Cloud cover 28).
Average visibility in September
Grand River, 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).
