September weather forecastAnnandale, VA
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Annandale, Virginia, with an average temperature fluctuating between 78.6°F (25.9°C) and 61.3°F (16.3°C).Temperature
September ushers in a minute temperature change, with average high-temperatures reducing from August's moderately hot 85.6°F (29.8°C) to a still warm 78.6°F (25.9°C). September's average low-temperature reading settles at a refreshing 61.3°F (16.3°C).Humidity
The average relative humidity in September in Annandale is 74%.Rainfall
In Annandale, during September, the rain falls for 12.7 days and regularly aggregates up to 2.09" (53mm) of precipitation. Throughout the year, in Annandale, there are 161.2 rainfall days, and 31.54" (801mm) of precipitation is accumulated.Snowfall
In Annandale, snow does not fall in May through October.Daylight
In September, the average length of the day in Annandale is 12h and 26min.On the first day of September, sunrise is at 6:38 am and sunset at 7:38 pm. On the last day of the month, sunrise is at 7:04 am and sunset at 6:52 pm EDT.
Sunshine
The average sunshine in September is 9.1h.UV index
The average daily maximum UV index in September in Annandale is 5. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for average individuals.Note: The average daily UV index of 5 in September transforms into the following instructions:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Annandale, VA
- Average high temperature in September: 78.6°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 (40.5°F).
- Average low temperature in September: 61.3°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 (27.1°F).
Average pressure in September
Annandale, 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
Annandale, VA
- Average wind speed in September: 5.4mph
The windiest month (with the highest average wind speed) is March (7.6mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in September
Annandale, VA
- Average humidity in September: 74%
The month with the highest relative humidity is October (77%).
The months with the lowest relative humidity are April and July (71%).
Average rainfall in September
Annandale, VA
- Average rainfall in September: 2.09"
The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is January (2.05").
Average rainfall days in September
Annandale, VA
- Average rainfall days in September: 12.7 days
The month with the highest number of rainy days is May (18.2 days).
The month with the least rainy days is November (8.9 days).
Average snowfall in September
Annandale, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.31").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Annandale, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.9 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
Annandale, 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 6min
The month with the most sunshine is July (Average sunshine: 10h and 54min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 12min).
Average sunshine days in September
Annandale, VA
- Average sunshine days in September: 15.6 days
The month with the most sunshine days is November (19.2 days).
The month with the least sunshine days is July (10.9 days).
Average UV index in September
Annandale, 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, November and December (UV index 2).
Average cloud cover in September
Annandale, 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
Annandale, 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).
