September weather forecastVienna, VA
September
Weather in September
September, the first month of the autumn in Vienna, is still a warm month, with temperature in the range of an average low of 60.6°F (15.9°C) and an average high of 78.4°F (25.8°C).Temperature
Vienna in September experiences a gentle temperature dip, with average high-temperatures reducing from a moderately hot 85.8°F (29.9°C) in August to a still warm 78.4°F (25.8°C). Nighttime temperature experiences an average drop to a refreshing 60.6°F (15.9°C) in September.Humidity
In September, the average relative humidity is 75%.Rainfall
September is the month with the least rainfall. Rain falls for 13.1 days and accumulates 2.01" (51mm) of precipitation.Snowfall
May through October are months without snowfall in Vienna.Daylight
In Vienna, 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 7:04 am and sunset at 6:52 pm EDT.
Sunshine
In Vienna, the average sunshine in September is 9h.UV index
The average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the average person.Note: In September, the maximum UV index of 5 translates into these guidelines:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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: 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
Vienna, 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
Vienna, 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
Vienna, 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
Vienna, 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).
