September weather forecastRoyal City, WA
September
Weather in September
September, the first month of the autumn in Royal City, is also a moderately hot month, with an average temperature fluctuating between 76.1°F (24.5°C) and 54.7°F (12.6°C).Temperature
In September, the meteorological conditions alter, with the average high-temperature shifting from a hot 88.3°F (31.3°C) in August to a moderately hot 76.1°F (24.5°C). Royal City reports a consistent average low-temperature of 54.7°F (12.6°C) throughout September nights.Humidity
The average relative humidity in September is 45%.Rainfall
In Royal City, in September, during 4.1 rainfall days, 0.31" (8mm) of precipitation is typically accumulated. Throughout the year, in Royal City, there are 86.4 rainfall days, and 6.38" (162mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through April, September, November and December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 22.3 snowfall days, and 10" (254mm) of snow is accumulated.Daylight
The average length of the day in September in Royal City is 12h and 32min.On the first day of the month, sunrise is at 6:19 am and sunset at 7:37 pm. On the last day of September, sunrise is at 6:57 am and sunset at 6:39 pm PDT.
Sunshine
In Royal City, the average sunshine in September is 10.8h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV rays for the average person.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Undertake protective steps - Recommendations to avoid sunburn are issued. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. During bright days, sunglasses that offer UVA and UVB defense are recommended. Foresee this! The reflection from snow can nearly double the intensity of UV radiation from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Royal City, WA
- Average high temperature in September: 76.1°F
The warmest months (with the highest average high temperature) are July and August (88.3°F).
The month with the lowest average high temperature is December (34.5°F).
- Average low temperature in September: 54.7°F
The month with the highest average low temperature is August (61.5°F).
The coldest month (with the lowest average low temperature) is December (24.3°F).
Average pressure in September
Royal City, WA
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.17"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in September
Royal City, WA
- Average wind speed in September: 6.3mph
The windiest month (with the highest average wind speed) is April (7.6mph).
The calmest month (with the lowest average wind speed) is December (4.7mph).
Average humidity in September
Royal City, WA
- Average humidity in September: 45%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is July (37%).
Average rainfall in September
Royal City, WA
- Average rainfall in September: 0.31"
The wettest months (with the highest rainfall) are January and December (0.87").
The driest month (with the least rainfall) is August (0.2").
Average rainfall days in September
Royal City, WA
- Average rainfall days in September: 4.1 days
The month with the highest number of rainy days is March (10.6 days).
The month with the least rainy days is August (3.5 days).
Average snowfall in September
Royal City, WA
- Average snowfall in September: 0.04"
The month with the highest snowfall is December (3.43").
The months with the least snowfall are May, June, July, August and October (0").
Average snowfall days in September
Royal City, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (6.5 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Royal City, 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: 10h and 48min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 4h and 54min).
Average sunshine days in September
Royal City, WA
- Average sunshine days in September: 24.3 days
The months with the most sunshine days are July and August (25.8 days).
The month with the least sunshine days is February (16 days).
Average UV index in September
Royal City, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Royal City, WA
- Average cloud cover in September: 16
The month with the most cloud cover is January (Cloud cover 47).
The months with the least cloud cover are July and August (Cloud cover 10).
Average visibility in September
Royal City, WA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (5mi).
