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
September sees a slight reduction in average high-temperature, with a shift from a moderately hot 85.6°F (29.8°C) in August to a still warm 78.6°F (25.9°C). The average low-temperature during September nights is an enjoyable 61.2°F (16.2°C).Humidity
In McLean, the average relative humidity in September is 74%.Rainfall
January and September are months with the least rain in McLean, Virginia, when the rain falls for 8.1 days and typically aggregates up to 0.51" (13mm) of rain.Snowfall
In McLean, snow does not fall in May through October.Daylight
The average length of the day in September in McLean, Virginia, 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, in McLean, sunrise is at 7:04 am and sunset at 6:52 pm EDT.
Sunshine
In McLean, the average sunshine in September is 9h.UV index
In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: The maximum daily UV index of 5 in September interprets into the following recommendations:
Make use of precautions - Suggestions to resist sunburn are communicated. To prevent harmful UV exposure, minimize direct contact with the Sun 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.
Frequently asked questions
What is the temperature in September in McLean?
What is the average humidity in September in McLean?
What is the driest month in McLean?
How many days does it rain in September in McLean?
When it does not snow in McLean?
How many hours of daylight does McLean have in September?
When is the sunrise / sunset in September in McLean?
How long on average sun shines in September in McLean?
How high is the UV index in September in McLean?
Average temperature in September
McLean, VA
- Average high temperature in September: 78.6°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (40.1°F).
- Average low temperature in September: 61.2°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 (26.8°F).
Average pressure in September
McLean, 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
McLean, 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
McLean, 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 (70%).
Average rainfall in September
McLean, VA
- Average rainfall in September: 0.51"
The wettest month (with the highest rainfall) is August (1.5").
The driest months (with the least rainfall) are January and September (0.51").
Average rainfall days in September
McLean, VA
- Average rainfall days in September: 8.1 days
The month with the highest number of rainy days is July (13.5 days).
The month with the least rainy days is November (5.6 days).
Average snowfall in September
McLean, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (0.98").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
McLean, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (3.6 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
McLean, VA
- Average daylight in September: 12h and 2min
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 54min).
The months with the least sunshine are February and December (Average sunshine: 5h and 6min).
Average sunshine days in September
McLean, VA
- Average sunshine days in September: 19.1 days
The month with the most sunshine days is November (23 days).
The month with the least sunshine days is July (14.3 days).
Average UV index in September
McLean, 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
McLean, 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
McLean, 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).
McLean, Virginia, USA
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