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's onset brings a slight change in high-temperatures, falling from a moderately hot 82.9°F (28.3°C) in August to an agreeable 71.6°F (22°C). Despite a significant disparity with daytime temperatures, an average low-temperature of 49.6°F (9.8°C) is recorded during September.Humidity
The average relative humidity in September in Rock Island is 52%.Rainfall
In Rock Island, in September, during 6 rainfall days, 0.59" (15mm) of precipitation is typically accumulated. In Rock Island, during the entire year, the rain falls for 111.7 days and collects up to 10.71" (272mm) of precipitation.Snowfall
Months with snowfall in Rock Island, Washington, are January through April, September, November and December. September is the first month it typically snows in Rock Island. Throughout September, in the average 0.1 snowfall days, it receives 0.28" (7mm) of snow. Throughout the year, in Rock Island, there are 31.6 snowfall days, and 18.86" (479mm) of snow is accumulated.Daylight
In September, the average length of the day is 12h and 32min.On the first day of September, sunrise is at 6:20 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 6:59 am and sunset at 6:41 pm PDT.
Sunshine
In September, the average sunshine in Rock Island is 10.8h.UV index
The average daily maximum UV index in September in Rock Island is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for average individuals.Note: An average maximum UV index of 4 in September leads to these recommendations:
Be cautious. Those with fair skin can be subjected to burns in fewer than 30 minutes. To protect against the Sun's most potent rays, avoid direct exposure around midday. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Frequently asked questions
What is the temperature in September in Rock Island?
What is the average humidity in September in Rock Island?
How many days does it rain in September in Rock Island?
When does it start to snow in Rock Island?
How many hours of daylight does Rock Island have in September?
What time are sunrise and sunset in September in Rock Island?
How long on average sun shines in September in Rock Island?
How high is the UV index 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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