September weather forecastMount Vernon, VA
September
Weather in September
September, the first month of the autumn in Mount Vernon, is also a moderately hot month, with an average temperature fluctuating between 78.6°F (25.9°C) and 61.7°F (16.5°C).Temperature
In September, the average high-temperature marginally decreases from a moderately hot 85.6°F (29.8°C) in August to a still warm 78.6°F (25.9°C). An average low-temperature of 61.7°F (16.5°C) is common during the nights of September.Humidity
In September, the average relative humidity is 74%.Rainfall
The month with the least rainfall in Mount Vernon is September, when the rain falls for 11.9 days and typically collects 1.93" (49mm) of precipitation.Snowfall
In Mount Vernon, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:38 am and sunset at 7:38 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:52 pm EDT.
Sunshine
In Mount Vernon, the average sunshine in September is 9h.UV index
The average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for average individuals.Note: A maximum high daily UV index of 5 during September translates into the following directions:
Ensure safety - Imperative it is to shield skin and eyes from damage. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mount Vernon, VA
- Average high temperature in September: 78.6°F
The warmest month (with the highest average high temperature) is July (87.8°F).
The month with the lowest average high temperature is January (40.6°F).
- Average low temperature in September: 61.7°F
The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).
Average pressure in September
Mount Vernon, VA
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in September
Mount Vernon, VA
- Average wind speed in September: 5.6mph
The windiest month (with the highest average wind speed) is March (7.8mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in September
Mount Vernon, VA
- Average humidity in September: 74%
The months with the highest relative humidity are May, October and December (76%).
The months with the lowest relative humidity are April and July (71%).
Average rainfall in September
Mount Vernon, VA
- Average rainfall in September: 1.93"
The wettest month (with the highest rainfall) is August (3.43").
The driest month (with the least rainfall) is September (1.93").
Average rainfall days in September
Mount Vernon, VA
- Average rainfall days in September: 11.9 days
The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is November (8.5 days).
Average snowfall in September
Mount Vernon, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.48").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Mount Vernon, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.5 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, VA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 9h and 0min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 6min).
Average sunshine days in September
Mount Vernon, VA
- Average sunshine days in September: 16.5 days
The month with the most sunshine days is November (19.8 days).
The month with the least sunshine days is May (11.5 days).
Average UV index in September
Mount Vernon, VA
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 2).
Average cloud cover in September
Mount Vernon, VA
- Average cloud cover in September: 36
The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in September
Mount Vernon, VA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
