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
In Rock Island, the average high-temperature in September decreases from a moderately hot 82.9°F (28.3°C) in August to an agreeable 71.6°F (22°C). In September, the temperature sees a substantial plunge from daytime highs to a low average of 49.6°F (9.8°C).Humidity
In September, the average relative humidity is 52%.Rainfall
In Rock Island, Washington, in September, during 6 rainfall days, 0.59" (15mm) of precipitation is typically accumulated. Throughout the year, there are 111.7 rainfall days, and 10.71" (272mm) of precipitation is accumulated.Snowfall
January through April, September, November and December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.28" (7mm) of snow. Throughout the year, there are 31.6 snowfall days, and 18.86" (479mm) of snow is accumulated.Daylight
The average length of the day in September is 12h and 32min.On the first day of the month, sunrise is at 6:20 am and sunset at 7:39 pm. On the last day of September, sunrise is at 6:59 am and sunset at 6:41 pm PDT.
Sunshine
In September, the average sunshine is 10.8h.UV index
In September, the average daily maximum UV index in Rock Island is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for average individuals.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Put precautions into practice - Protective measures against sun-induced damage are advised. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage. Notice this! Nearly double the intensity of the Sun's UV radiation can be caused by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How many days does it rain in September?
When does it start to snow?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Rock Island have in September?
What is the UV index intensity in September in Rock Island?
Average temperature in September
Rock Island, WA
- Average high temperature in September: 71.6°F
The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is December (32.4°F).
- Average low temperature in September: 49.6°F
The month with the highest average low temperature is August (56.3°F).
The coldest month (with the lowest average low temperature) is December (20.7°F).
Average pressure in September
Rock Island, WA
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is August (29.93"Hg).
Average wind speed in September
Rock Island, WA
- Average wind speed in September: 5.4mph
The windiest month (with the highest average wind speed) is June (6.5mph).
The calmest month (with the lowest average wind speed) is December (3.7mph).
Average humidity in September
Rock Island, WA
- Average humidity in September: 52%
The month with the highest relative humidity is January (88%).
The months with the lowest relative humidity are July and August (44%).
Average rainfall in September
Rock Island, WA
- Average rainfall in September: 0.59"
The wettest months (with the highest rainfall) are January and December (1.57").
The driest months (with the least rainfall) are July and August (0.24").
Average rainfall days in September
Rock Island, WA
- Average rainfall days in September: 6 days
The month with the highest number of rainy days is March (13.8 days).
The month with the least rainy days is August (3.8 days).
Average snowfall in September
Rock Island, WA
- Average snowfall in September: 0.28"
The month with the highest snowfall is December (5.98").
The months with the least snowfall are May, June, July, August and October (0").
Average snowfall days in September
Rock Island, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (9.5 days).
The months with the least snowfall days are May, June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Rock Island, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 10h and 5min
The month with the most sunshine is August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).
Average sunshine days in September
Rock Island, WA
- Average sunshine days in September: 22.2 days
The month with the most sunshine days is July (25.5 days).
The month with the least sunshine days is February (12.6 days).
Average UV index in September
Rock Island, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Rock Island, WA
- Average cloud cover in September: 18
The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are July and August (Cloud cover 11).
Average visibility in September
Rock Island, WA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
Rock Island, Washington, USA
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