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
With the arrival of September, West Lake Sammamish experiences a modest decline in average high-temperatures, transitioning from a moderately hot 76.5°F (24.7°C) in August to an agreeable 69.8°F (21°C). September witnesses an average nighttime temperature of 48.9°F (9.4°C) in West Lake Sammamish.Humidity
In September, the average relative humidity is 75%.Rainfall
In West Lake Sammamish, during September, the rain falls for 10.1 days and regularly aggregates up to 1.06" (27mm) of precipitation. Throughout the year, in West Lake Sammamish, Washington, there are 136.7 rainfall days, and 13.39" (340mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Daylight
The average length of the day in September in West Lake Sammamish is 12h and 33min.On the first day of the month, sunrise is at 6:28 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:07 am and sunset at 6:49 pm PDT.
Sunshine
In West Lake Sammamish, Washington, the average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September in West Lake Sammamish is 3. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for average individuals.Note: The daily maximum UV index of 3 in September interprets into the following advice:
Take precautions - Protection against sunburn is recommended. To guard against the harmful effects of the Sun, minimize exposure during midday. Protect your eyes, ears, face, and neck from the Sun by wearing a wide-brimmed hat. Be mindful! The reflection from snow can increase the Sun's UV radiation nearly twice.
Frequently asked questions
What are September temperatures in West Lake Sammamish?
What is the average humidity in September in West Lake Sammamish?
How much does it rain in West Lake Sammamish in September?
When it does not snow in West Lake Sammamish?
What is the average length of the day in September in West Lake Sammamish?
What time are sunrise and sunset in September in West Lake Sammamish?
How many hours of sunshine does West Lake Sammamish have in September?
What is the UV index reading in September in West Lake Sammamish?
Average temperature in September
West Lake Sammamish, WA
- Average high temperature in September: 69.8°F
The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (42.3°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 December (33.6°F).
Average pressure in September
West Lake Sammamish, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in September
West Lake Sammamish, WA
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (5mph).
The calmest month (with the lowest average wind speed) is August (3.4mph).
Average humidity in September
West Lake Sammamish, WA
- Average humidity in September: 75%
The months with the highest relative humidity are January, February and December (85%).
The month with the lowest relative humidity is July (70%).
Average rainfall in September
West Lake Sammamish, WA
- Average rainfall in September: 1.06"
The wettest month (with the highest rainfall) is December (1.85").
The driest months (with the least rainfall) are July and August (0.35").
Average rainfall days in September
West Lake Sammamish, WA
- Average rainfall days in September: 10.1 days
The month with the highest number of rainy days is March (14.8 days).
The month with the least rainy days is August (5.2 days).
Average snowfall in September
West Lake Sammamish, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
West Lake Sammamish, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (3.2 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
West Lake Sammamish, 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 1min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are January and December (Average sunshine: 4h and 12min).
Average sunshine days in September
West Lake Sammamish, WA
- Average sunshine days in September: 17.7 days
The month with the most sunshine days is August (24 days).
The month with the least sunshine days is November (13.5 days).
Average UV index in September
West Lake Sammamish, WA
- Average UV index in September: 3
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
West Lake Sammamish, 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 26).
Average visibility in September
West Lake Sammamish, 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).
West Lake Sammamish, Washington, USA
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