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
September witnesses a gentle descent in average high-temperature, descending from August's 80.4°F (26.9°C) to a still moderately hot 74.3°F (23.5°C). Throughout September, Rock Valley witnesses a consistent average low-temperature of 54°F (12.2°C).Humidity
The average relative humidity in September is 71%.Rainfall
In Rock Valley, during September, the rain falls for 11.8 days and regularly aggregates up to 2.2" (56mm) of precipitation. Throughout the year, there are 130 rainfall days, and 24.09" (612mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall in Rock Valley, Iowa.Daylight
In September, the average length of the day in Rock Valley is 12h and 29min.On the first day of September, sunrise is at 6:50 am and sunset at 7:59 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 7:07 pm CDT.
Sunshine
In Rock Valley, Iowa, the average sunshine in September is 8.9h.UV index
In September, the average daily maximum UV index in Rock Valley, Iowa, is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Put precautions into practice - Guidance to elude sunburn is provided. The Sun's radiation is especially intense around midday; try to stay in shade during this period. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in Rock Valley?
What is the average humidity in September in Rock Valley?
How much does it rain in Rock Valley in September?
When it does not snow in Rock Valley?
Does it snow in Rock Valley in September?
What is the average length of the day in September in Rock Valley?
When is the sunrise / sunset in September in Rock Valley?
How many hours of sunshine does Rock Valley have in September?
How high is the UV index in September in Rock Valley?
Average temperature in September
Rock Valley, IA
- Average high temperature in September: 74.3°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (24.1°F).
- Average low temperature in September: 54°F
The month with the highest average low temperature is July (63.5°F).
The coldest month (with the lowest average low temperature) is January (10.8°F).
Average pressure in September
Rock Valley, IA
- Average pressure in September: 29.98"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
Rock Valley, IA
- Average wind speed in September: 9.2mph
The windiest month (with the highest average wind speed) is April (11.2mph).
The calmest month (with the lowest average wind speed) is July (7.8mph).
Average humidity in September
Rock Valley, IA
- Average humidity in September: 71%
The month with the highest relative humidity is January (87%).
The month with the lowest relative humidity is October (67%).
Average rainfall in September
Rock Valley, IA
- Average rainfall in September: 2.2"
The wettest month (with the highest rainfall) is June (3.78").
The driest month (with the least rainfall) is January (0.75").
Average rainfall days in September
Rock Valley, IA
- Average rainfall days in September: 11.8 days
The month with the highest number of rainy days is June (18.8 days).
The month with the least rainy days is February (3.3 days).
Average snowfall in September
Rock Valley, IA
- Average snowfall in September: 0"
The month with the highest snowfall is February (4.49").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Rock Valley, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Rock Valley, IA
- Average daylight in September: 12h and 3min
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 0min).
- Average sunshine in September: 8h and 5min
The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in September
Rock Valley, IA
- Average sunshine days in September: 15.3 days
The month with the most sunshine days is November (19.7 days).
The month with the least sunshine days is June (8.3 days).
Average UV index in September
Rock Valley, 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, February, October, November and December (UV index 2).
Average cloud cover in September
Rock Valley, IA
- Average cloud cover in September: 29
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is July (Cloud cover 27).
Average visibility in September
Rock Valley, 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).
Rock Valley, Iowa, USA
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