Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
During the shift to September, River Sioux records a mild decrease in average high-temperature, moving from 82.2°F (27.9°C) in August to a still warm 76.5°F (24.7°C). River Sioux's temperature lowers to a mean of 56.3°F (13.5°C) during the nights in September.Humidity
The average relative humidity in September is 71%.Rainfall
In River Sioux, in September, during 12.1 rainfall days, 2.09" (53mm) of precipitation is typically accumulated. In River Sioux, during the entire year, the rain falls for 125.1 days and collects up to 22.64" (575mm) of precipitation.Snowfall
In River Sioux, snow does not fall in June through September.Daylight
In River Sioux, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:50 am and sunset at 7:57 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 7:06 pm CDT.
Sunshine
In September, the average sunshine is 9h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for the average person.Note: In September, the UV index of 4 transforms into the following advice:
Guard yourself - Precautionary measures against sun damage are advocated. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September in River Sioux?
How much does it rain in September?
When it does not snow in River Sioux?
Does it snow in September?
How many hours of daylight does River Sioux have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
River Sioux, IA
- Average high temperature in September: 76.5°F
The warmest month (with the highest average high temperature) is July (84.4°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (15.3°F).
Average pressure in September
River Sioux, 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
River Sioux, IA
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest month (with the lowest average wind speed) is July (7.2mph).
Average humidity in September
River Sioux, IA
- Average humidity in September: 71%
The month with the highest relative humidity is January (81%).
The month with the lowest relative humidity is October (66%).
Average rainfall in September
River Sioux, IA
- Average rainfall in September: 2.09"
The wettest month (with the highest rainfall) is May (3.5").
The driest month (with the least rainfall) is January (0.71").
Average rainfall days in September
River Sioux, IA
- Average rainfall days in September: 12.1 days
The month with the highest number of rainy days is June (16.8 days).
The month with the least rainy days is February (3.3 days).
Average snowfall in September
River Sioux, IA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.8").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
River Sioux, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.4 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
River Sioux, IA
- Average daylight in September: 12h and 3min
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 0min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).
Average sunshine days in September
River Sioux, IA
- Average sunshine days in September: 15.8 days
The month with the most sunshine days is November (20.7 days).
The month with the least sunshine days is June (11.3 days).
Average UV index in September
River Sioux, 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
River Sioux, IA
- Average cloud cover in September: 28
The month with the most cloud cover is January (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 25).
Average visibility in September
River Sioux, 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).
River Sioux, Iowa, USA
Weather forecast for your location
2. Allow the app to use your location