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
The move into September indicates a slight reduction in the average high-temperature, down from August's 85.8°F (29.9°C) to a still warm 78.4°F (25.8°C). Fairfax reports an average nighttime low-temperature of 60.6°F (15.9°C) in September.Humidity
In September, the average relative humidity in Fairfax is 75%.Rainfall
The month with the least rainfall in Fairfax is September, when the rain falls for 13.1 days and typically collects 2.01" (51mm) of precipitation.Snowfall
In Fairfax, snow does not fall in May through October.Daylight
In Fairfax, the average length of the day in September is 12h and 26min.On the first day of September in Fairfax, sunrise is at 6:38 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:04 am and sunset at 6:53 pm EDT.
Sunshine
The average sunshine in September is 9h.UV index
The average daily maximum UV index in September in Fairfax is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for average individuals.Note: The maximum UV index of 5 during September leads to these instructions:
Undertake protective steps - Recommendations to avoid sunburn are issued. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. A hat with a broad brim is indispensable, filtering out up to half of UV rays.
Frequently asked questions
What is the usual temperature for Fairfax in September?
What is the average humidity in September in Fairfax?
What is the driest month in Fairfax?
How much does it rain in Fairfax in September?
When it does not snow in Fairfax?
What is the average length of the day in September in Fairfax?
What time are sunrise and sunset in September in Fairfax?
How many hours of sunshine does Fairfax have in September?
What is the UV index intensity in September in Fairfax?
Average temperature in September
Fairfax, VA
- Average high temperature in September: 78.4°F
The warmest month (with the highest average high temperature) is July (88°F).
The month with the lowest average high temperature is January (40.5°F).
- Average low temperature in September: 60.6°F
The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).
Average pressure in September
Fairfax, 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
Fairfax, VA
- Average wind speed in September: 5.3mph
The windiest month (with the highest average wind speed) is March (7.4mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).
Average humidity in September
Fairfax, VA
- Average humidity in September: 75%
The months with the highest relative humidity are October and December (77%).
The month with the lowest relative humidity is July (71%).
Average rainfall in September
Fairfax, VA
- Average rainfall in September: 2.01"
The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is September (2.01").
Average rainfall days in September
Fairfax, VA
- Average rainfall days in September: 13.1 days
The months with the highest number of rainy days are May and August (17.3 days).
The month with the least rainy days is November (9.1 days).
Average snowfall in September
Fairfax, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Fairfax, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.6 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
Fairfax, VA
- Average daylight in September: 12h and 2min
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 months with the least sunshine are January, February and December (Average sunshine: 5h and 12min).
Average sunshine days in September
Fairfax, VA
- Average sunshine days in September: 15.7 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (11.3 days).
Average UV index in September
Fairfax, 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, February, November and December (UV index 2).
Average cloud cover in September
Fairfax, VA
- Average cloud cover in September: 37
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
Fairfax, 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).
Fairfax, Virginia, USA
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