September weather forecastRoy, WA
September
Weather in September
The first month of the autumn, September, is still a pleasant month in Roy, Washington, with an average temperature ranging between min 48.9°F (9.4°C) and max 70.7°F (21.5°C).Temperature
September's onset brings a negligible change in high-temperatures, falling from a warm 78.4°F (25.8°C) in August to an agreeable 70.7°F (21.5°C). September nights in Roy report a substantial dip from daytime highs to an average of 48.9°F (9.4°C).Humidity
The average relative humidity in September is 76%.Rainfall
In September, in Roy, the rain falls for 12 days. Throughout September, 1.65" (42mm) of precipitation is accumulated. Throughout the year, there are 174.2 rainfall days, and 31.06" (789mm) of precipitation is accumulated.Snowfall
In Roy, snow does not fall in May through October.Daylight
In September, the average length of the day in Roy is 12h and 32min.On the first day of the month, sunrise is at 6:30 am and sunset at 7:49 pm. On the last day of September, sunrise is at 7:08 am and sunset at 6:50 pm PDT.
Sunshine
In Roy, the average sunshine in September is 9h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the ordinary person.Note: The maximum daily UV index of 4 during September translates into the following directions:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Roy, WA
- Average high temperature in September: 70.7°F
The warmest month (with the highest average high temperature) is August (78.4°F).
The month with the lowest average high temperature is December (43.5°F).
- Average low temperature in September: 48.9°F
The month with the highest average low temperature is August (52.2°F).
The coldest month (with the lowest average low temperature) is February (34°F).
Average pressure in September
Roy, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.01"Hg).
Average wind speed in September
Roy, WA
- Average wind speed in September: 3.9mph
The windiest month (with the highest average wind speed) is March (5mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity in September
Roy, WA
- Average humidity in September: 76%
The month with the highest relative humidity is January (88%).
The month with the lowest relative humidity is July (69%).
Average rainfall in September
Roy, WA
- Average rainfall in September: 1.65"
The wettest month (with the highest rainfall) is December (4.96").
The driest month (with the least rainfall) is July (0.35").
Average rainfall days in September
Roy, WA
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is March (19.7 days).
The month with the least rainy days is August (5.2 days).
Average snowfall in September
Roy, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.73").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Roy, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.8 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
Roy, WA
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is December (Average sunshine: 3h and 54min).
Average sunshine days in September
Roy, WA
- Average sunshine days in September: 15.6 days
The month with the most sunshine days is August (22.9 days).
The month with the least sunshine days is November (9.1 days).
Average UV index in September
Roy, 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
Roy, WA
- Average cloud cover in September: 37
The months with the most cloud cover are January and December (Cloud cover 59).
The months with the least cloud cover are July and August (Cloud cover 28).
Average visibility in September
Roy, WA
- Average visibility in September: 5mi
The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).
