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 signals a slight drop in average high-temperature, sliding from August's pleasant 73°F (22.8°C) to a comfortable 67.1°F (19.5°C). Throughout September nights, John Sam Lake registers an average low-temperature of 50°F (10°C).Humidity
The average relative humidity in September is 77%.Rainfall
In John Sam Lake, during September, the rain falls for 12.3 days and regularly aggregates up to 1.77" (45mm) of precipitation. Throughout the year, there are 179.1 rainfall days, and 29.57" (751mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Daylight
The average length of the day in September is 12h and 33min.On the first day of September, sunrise is at 6:28 am and sunset at 7:49 pm. On the last day of the month, sunrise is at 7:08 am and sunset at 6:49 pm PDT.
Sunshine
In September, the average sunshine in John Sam Lake is 9.2h.UV index
In John Sam Lake, Washington, the average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for ordinary individuals.Note: In September, the maximum UV index of 3 translates into these guidelines:
Ensure safety - Recommendations to avert sunburn are presented. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
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?
When are sunrise and sunset in September in John Sam Lake?
How many hours of sunshine does John Sam Lake have in September?
What is the UV index reading in September?
Average temperature in September
John Sam Lake, WA
- Average high temperature in September: 67.1°F
The warmest month (with the highest average high temperature) is August (73°F).
The month with the lowest average high temperature is December (42.3°F).
- Average low temperature in September: 50°F
The month with the highest average low temperature is August (52.5°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).
Average pressure in September
John Sam Lake, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in September
John Sam Lake, WA
- Average wind speed in September: 4mph
The windiest months (with the highest average wind speed) are March and November (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in September
John Sam Lake, WA
- Average humidity in September: 77%
The months with the highest relative humidity are January and December (85%).
The month with the lowest relative humidity is July (73%).
Average rainfall in September
John Sam Lake, WA
- Average rainfall in September: 1.77"
The wettest month (with the highest rainfall) is November (4.06").
The driest month (with the least rainfall) is July (0.47").
Average rainfall days in September
John Sam Lake, WA
- Average rainfall days in September: 12.3 days
The month with the highest number of rainy days is March (19.8 days).
The month with the least rainy days is August (6.1 days).
Average snowfall in September
John Sam Lake, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.68").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
John Sam Lake, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.1 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
John Sam Lake, WA
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is August (Average sunshine: 10h and 36min).
The months with the least sunshine are January and December (Average sunshine: 4h and 12min).
Average sunshine days in September
John Sam Lake, WA
- Average sunshine days in September: 16.1 days
The month with the most sunshine days is August (23.1 days).
The months with the least sunshine days are February and November (8.6 days).
Average UV index in September
John Sam Lake, 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
John Sam Lake, 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
John Sam Lake, WA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, November and December (5mi).
John Sam Lake, Washington, USA
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