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
The advent of September signifies a minor shift to an average high-temperature of a still warm 75.4°F (24.1°C), aligning closely with August. September brings Riverdale a consistent average low-temperature of 56.3°F (13.5°C).Humidity
The average relative humidity in September is 76%.Rainfall
In Riverdale, in September, it is raining for 6.9 days, with typically 0.75" (19mm) of accumulated precipitation. In Riverdale, during the entire year, the rain falls for 99.4 days and collects up to 9.57" (243mm) of precipitation.Snowfall
January through April, September through December are months with snowfall in Riverdale. September is the first month it typically snows in Riverdale. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. In Riverdale, during the entire year, snow falls for 24.5 days and aggregates up to 4.09" (104mm) of snow.Daylight
In Riverdale, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:28 am and sunset at 7:34 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:44 pm CDT.
Sunshine
In September, the average sunshine is 9.1h.UV index
In September, the average daily maximum UV index in Riverdale is 4. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: An average maximum UV index of 4 in September leads to these recommendations:
Exercise prevention - Protecting skin and eyes from harm is required. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in Riverdale?
What is the average humidity in September in Riverdale?
How many days does it rain in September in Riverdale?
When does it start snowing in Riverdale?
What is the average length of the day in September in Riverdale?
What time are sunrise and sunset in September in Riverdale?
How many hours of sunshine does Riverdale have in September?
What is the UV index intensity in September in Riverdale?
Average temperature in September
Riverdale, IA
- Average high temperature in September: 75.4°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 (28.2°F).
- Average low temperature in September: 56.3°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (15.4°F).
Average pressure in September
Riverdale, IA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Riverdale, IA
- Average wind speed in September: 7.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.7mph).
Average humidity in September
Riverdale, IA
- Average humidity in September: 76%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in September
Riverdale, IA
- Average rainfall in September: 0.75"
The wettest month (with the highest rainfall) is May (1.61").
The driest month (with the least rainfall) is December (0.35").
Average rainfall days in September
Riverdale, IA
- Average rainfall days in September: 6.9 days
The month with the highest number of rainy days is May (13.4 days).
The month with the least rainy days is January (3.2 days).
Average snowfall in September
Riverdale, IA
- Average snowfall in September: 0.04"
The month with the highest snowfall is January (1.26").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in September
Riverdale, IA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Riverdale, IA
- Average daylight in September: 12h and 3min
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 12min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Riverdale, IA
- Average sunshine days in September: 20.9 days
The month with the most sunshine days is December (22.4 days).
The month with the least sunshine days is June (14.4 days).
Average UV index in September
Riverdale, IA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in September
Riverdale, IA
- Average cloud cover in September: 31
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in September
Riverdale, 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).
Riverdale, Iowa, USA
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