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 September's arrival, Mount Vernon's weather records an average high-temperature of a comfortable 64°F (17.8°C), marking little difference from August's 68.4°F (20.2°C). The average nighttime temperature in Mount Vernon lowers to a fresh 51.4°F (10.8°C) throughout September.Humidity
In Mount Vernon, the average relative humidity in September is 79%.Rainfall
In September, the rain falls for 12.1 days. Throughout September, 2.24" (57mm) of precipitation is accumulated. In Mount Vernon, during the entire year, the rain falls for 185.2 days and collects up to 34.72" (882mm) of precipitation.Snowfall
In Mount Vernon, Washington, snow does not fall in May through October.Daylight
In September, the average length of the day is 12h and 34min.On the first day of the month, sunrise is at 6:28 am and sunset at 7:50 pm. On the last day of September, in Mount Vernon, sunrise is at 7:08 am and sunset at 6:49 pm PDT.
Sunshine
In Mount Vernon, the average sunshine in September is 9h.UV index
In September, the average daily maximum UV index in Mount Vernon is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum daily UV index of 4 in September converts into the following recommendations:
Exercise prevention - Protecting skin and eyes from harm is required. Exposing oneself to the midday Sun can be harmful due to the strong UV radiation; limit your time outside. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Frequently asked questions
What is the average September temperature in Mount Vernon?
What is the average humidity in September in Mount Vernon?
How many days does it rain in September in Mount Vernon?
When it does not snow in Mount Vernon?
What is the average length of the day in September in Mount Vernon?
What time are sunrise and sunset in September in Mount Vernon?
How many hours of sunshine does Mount Vernon have in September?
What is the UV index intensity in September in Mount Vernon?
Average temperature in September
Mount Vernon, WA
- Average high temperature in September: 64°F
The warmest months (with the highest average high temperature) are July and August (68.4°F).
The month with the lowest average high temperature is December (42.6°F).
- Average low temperature in September: 51.4°F
The month with the highest average low temperature is August (54.1°F).
The coldest month (with the lowest average low temperature) is February (36.1°F).
Average pressure in September
Mount Vernon, 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
Mount Vernon, WA
- Average wind speed in September: 4.5mph
The windiest month (with the highest average wind speed) is November (7.5mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity in September
Mount Vernon, WA
- Average humidity in September: 79%
The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is July (75%).
Average rainfall in September
Mount Vernon, WA
- Average rainfall in September: 2.24"
The wettest month (with the highest rainfall) is November (4.96").
The driest month (with the least rainfall) is July (0.63").
Average rainfall days in September
Mount Vernon, WA
- Average rainfall days in September: 12.1 days
The month with the highest number of rainy days is March (20.8 days).
The month with the least rainy days is August (7.2 days).
Average snowfall in September
Mount Vernon, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Mount Vernon, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.6 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
Mount Vernon, 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 0min
The months with the most sunshine are July and August (Average sunshine: 10h and 24min).
The month with the least sunshine is December (Average sunshine: 3h and 54min).
Average sunshine days in September
Mount Vernon, WA
- Average sunshine days in September: 16.3 days
The month with the most sunshine days is August (22.3 days).
The month with the least sunshine days is November (8.1 days).
Average UV index in September
Mount Vernon, WA
- Average UV index in September: 4
The month with the highest UV index is 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
Mount Vernon, WA
- Average cloud cover in September: 34
The month with the most cloud cover is December (Cloud cover 59).
The month with the least cloud cover is August (Cloud cover 26).
Average visibility in September
Mount Vernon, WA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Mount Vernon, Washington, USA
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