September weather forecastCastle Rock, WA
September
Weather in September
September, the first month of the autumn in Castle Rock, is also an agreeable month, with an average temperature fluctuating between 70.7°F (21.5°C) and 47.1°F (8.4°C).Temperature
September's arrival aligns with a minor decrease in average high-temperatures, from August's warm 77.7°F (25.4°C) to a pleasant 70.7°F (21.5°C). In the month of September, Castle Rock witnesses a marked temperature drop at night, averaging a low of 47.1°F (8.4°C).Humidity
The average relative humidity in September in Castle Rock is 78%.Rainfall
In Castle Rock, in September, during 10.3 rainfall days, 0.94" (24mm) of precipitation is typically accumulated. In Castle Rock, during the entire year, the rain falls for 157.3 days and collects up to 16.54" (420mm) of precipitation.Snowfall
In Castle Rock, snow does not fall in April through October.Daylight
The average length of the day in September in Castle Rock is 12h and 31min.On the first day of the month, sunrise is at 6:33 am and sunset at 7:49 pm. On the last day of September, in Castle Rock, sunrise is at 7:09 am and sunset at 6:52 pm PDT.
Sunshine
In Castle Rock, the average sunshine in September is 8.5h.UV index
In Castle Rock, the average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the average person.Note: The maximum daily UV index of 4 in September converts into the following recommendations:
Preventative actions are necessary - The mandate to avoid skin and eye damage is in place. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Castle Rock, WA
- Average high temperature in September: 70.7°F
The warmest month (with the highest average high temperature) is August (77.7°F).
The month with the lowest average high temperature is December (42.4°F).
- Average low temperature in September: 47.1°F
The month with the highest average low temperature is August (49.6°F).
The coldest month (with the lowest average low temperature) is December (32.5°F).
Average pressure in September
Castle Rock, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).
Average wind speed in September
Castle Rock, WA
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (4.8mph).
The calmest months (with the lowest average wind speed) are August and September (3.7mph).
Average humidity in September
Castle Rock, WA
- Average humidity in September: 78%
The months with the highest relative humidity are February and November (89%).
The months with the lowest relative humidity are July and August (73%).
Average rainfall in September
Castle Rock, WA
- Average rainfall in September: 0.94"
The wettest month (with the highest rainfall) is January (2.28").
The driest month (with the least rainfall) is August (0.31").
Average rainfall days in September
Castle Rock, WA
- Average rainfall days in September: 10.3 days
The month with the highest number of rainy days is March (17.5 days).
The month with the least rainy days is July (6.1 days).
Average snowfall in September
Castle Rock, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.02").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Castle Rock, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.4 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Castle Rock, WA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in September: 8h and 30min
The month with the most sunshine is August (Average sunshine: 10h and 18min).
The month with the least sunshine is February (Average sunshine: 3h and 30min).
Average sunshine days in September
Castle Rock, WA
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is August (21.9 days).
The month with the least sunshine days is April (10.5 days).
Average UV index in September
Castle Rock, WA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Castle Rock, WA
- Average cloud cover in September: 45
The month with the most cloud cover is February (Cloud cover 65).
The month with the least cloud cover is August (Cloud cover 37).
Average visibility in September
Castle Rock, WA
- Average visibility in September: 4mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (4mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (4mi).
