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 implies a soft temperature shift, with average high-temperatures reducing from August's moderately hot 77.5°F (25.3°C) to an agreeable 70°F (21.1°C). In September, Federal Way experiences an average nighttime temperature of 49.1°F (9.5°C).Humidity
In September, the average relative humidity is 74%.Rainfall
In September, the rain falls for 12.5 days. Throughout September, 1.61" (41mm) of precipitation is accumulated. In Federal Way, during the entire year, the rain falls for 177.2 days and collects up to 30.79" (782mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
The average length of the day in September is 12h and 32min.On the first day of September in Federal Way, sunrise is at 6:29 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:49 pm PDT.
Sunshine
The average sunshine in September is 9.3h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.Note: A maximum high daily UV index of 4 during September translates into the following directions:
Preventative actions are necessary - Suggestions to safeguard against sun damage are in order. Avoiding the Sun during its peak radiation time around midday is a healthy practice. Always opt for UVA and UVB-resistant sunglasses on radiant days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Federal Way have in September?
What is the UV index intensity in September?
Average temperature in September
Federal Way, WA
- Average high temperature in September: 70°F
The warmest month (with the highest average high temperature) is August (77.5°F).
The month with the lowest average high temperature is December (42.6°F).
- Average low temperature in September: 49.1°F
The month with the highest average low temperature is August (52.9°F).
The coldest month (with the lowest average low temperature) is December (34.2°F).
Average pressure in September
Federal Way, 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 March, August and September (30.01"Hg).
Average wind speed in September
Federal Way, WA
- Average wind speed in September: 3.8mph
The windiest month (with the highest average wind speed) is March (5.1mph).
The calmest months (with the lowest average wind speed) are July and August (3.5mph).
Average humidity in September
Federal Way, WA
- Average humidity in September: 74%
The months with the highest relative humidity are January and December (86%).
The month with the lowest relative humidity is July (68%).
Average rainfall in September
Federal Way, WA
- Average rainfall in September: 1.61"
The wettest month (with the highest rainfall) is December (4.72").
The driest month (with the least rainfall) is July (0.43").
Average rainfall days in September
Federal Way, WA
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is March (20 days).
The month with the least rainy days is August (5.9 days).
Average snowfall in September
Federal Way, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.27").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Federal Way, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (4.4 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
Federal Way, 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: 9h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).
Average sunshine days in September
Federal Way, WA
- Average sunshine days in September: 15.5 days
The month with the most sunshine days is August (22.8 days).
The months with the least sunshine days are February and November (8.5 days).
Average UV index in September
Federal Way, 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
Federal Way, WA
- Average cloud cover in September: 34
The month with the most cloud cover is December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in September
Federal Way, WA
- Average visibility in September: 6mi
The months with the highest visibility are June, July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, October, November and December (5mi).
Federal Way, Washington, USA
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