September weather forecastReston, VA
September
Weather in September
September, the first month of the autumn in Reston, is also a moderately hot month, with an average temperature fluctuating between 60.8°F (16°C) and 78.4°F (25.8°C).Temperature
Reston, Virginia, in September undergoes a slight reduction in the average high-temperature, shifting from August's 85.6°F (29.8°C) to a still moderately hot 78.4°F (25.8°C). An average low-temperature of 60.8°F (16°C) is observed during September nights.Humidity
In September, the average relative humidity is 74%.Rainfall
In Reston, Virginia, during September, the rain falls for 12.5 days and regularly aggregates up to 1.93" (49mm) of precipitation. In Reston, during the entire year, the rain falls for 152.8 days and collects up to 27.64" (702mm) of precipitation.Snowfall
In Reston, snow does not fall in May through October.Daylight
In Reston, Virginia, 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 7:39 pm. On the last day of September, sunrise is at 7:05 am and sunset at 6:53 pm EDT.
Sunshine
In Reston, the average sunshine in September is 8.7h.UV index
In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV rays for ordinary individuals.Note: The UV index of 5 during September leads to these advisories:
Undertake protective steps - Recommendations to avoid sunburn are issued. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Employ a hat with a wide brim for robust protection, cutting UV exposure by half.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Reston, VA
- Average high temperature in September: 78.4°F
The warmest month (with the highest average high temperature) is July (87.6°F).
The month with the lowest average high temperature is January (39.7°F).
- Average low temperature in September: 60.8°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).
Average pressure in September
Reston, 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
Reston, VA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is March (7.7mph).
The calmest month (with the lowest average wind speed) is August (4.9mph).
Average humidity in September
Reston, VA
- Average humidity in September: 74%
The months with the highest relative humidity are October and December (76%).
The month with the lowest relative humidity is July (69%).
Average rainfall in September
Reston, VA
- Average rainfall in September: 1.93"
The wettest month (with the highest rainfall) is August (3.39").
The driest month (with the least rainfall) is January (1.77").
Average rainfall days in September
Reston, VA
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is November (9.3 days).
Average snowfall in September
Reston, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.28").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Reston, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.6 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
Reston, VA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in September: 8h and 42min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 0min).
Average sunshine days in September
Reston, VA
- Average sunshine days in September: 16.3 days
The month with the most sunshine days is November (19.3 days).
The month with the least sunshine days is May (12.8 days).
Average UV index in September
Reston, 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
Reston, VA
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in September
Reston, 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).
