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
In Herndon, the average high-temperature in September gently drops from 82°F (27.8°C) in August to a still moderately hot 75.9°F (24.4°C). Nighttime temperatures exhibit a substantial dip from daytime highs during September, averaging at a fresh 54.1°F (12.3°C).Humidity
In Herndon, the average relative humidity in September is 78%.Rainfall
September is the month with the least rainfall. Rain falls for 15.5 days and accumulates 1.57" (40mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
The average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 6:56 am and sunset at 7:53 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 7:09 pm EDT.
Sunshine
In September, the average sunshine is 8.3h.UV index
In Herndon, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unprotected exposure to Sun's UV rays for the average person.Note: The maximum daily UV index of 4 during September translates into the following directions:
Exercise caution. The susceptibility of light skin individuals to burns is less than 30 minutes. Avoiding the Sun's peak radiation during midday hours is essential for health and safety. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
What is the driest month?
How much does it rain in September?
When it does not snow in Herndon?
Does it snow in September?
What is the average length of the day in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
Herndon, WV
- Average high temperature in September: 75.9°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (38.3°F).
- Average low temperature in September: 54.1°F
The month with the highest average low temperature is July (60.1°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).
Average pressure in September
Herndon, WV
- Average pressure in September: 30.06"Hg
The month with the highest atmospheric pressure is November (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.99"Hg).
Average wind speed in September
Herndon, WV
- Average wind speed in September: 4.5mph
The windiest month (with the highest average wind speed) is January (7.4mph).
The calmest month (with the lowest average wind speed) is August (4.2mph).
Average humidity in September
Herndon, WV
- Average humidity in September: 78%
The month with the highest relative humidity is February (83%).
The months with the lowest relative humidity are June, July, August and November (77%).
Average rainfall in September
Herndon, WV
- Average rainfall in September: 1.57"
The wettest months (with the highest rainfall) are February and May (3.43").
The driest month (with the least rainfall) is September (1.57").
Average rainfall days in September
Herndon, WV
- Average rainfall days in September: 15.5 days
The month with the highest number of rainy days is May (20.1 days).
The month with the least rainy days is November (11.3 days).
Average snowfall in September
Herndon, WV
- Average snowfall in September: 0"
The month with the highest snowfall is February (6.02").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Herndon, WV
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Herndon, WV
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in September: 8h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Herndon, WV
- Average sunshine days in September: 12.1 days
The month with the most sunshine days is November (15.8 days).
The month with the least sunshine days is February (8.3 days).
Average UV index in September
Herndon, WV
- Average UV index in September: 4
The months with the highest UV index are June 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
Herndon, WV
- Average cloud cover in September: 40
The month with the most cloud cover is January (Cloud cover 62).
The month with the least cloud cover is August (Cloud cover 36).
Average visibility in September
Herndon, WV
- Average visibility in September: 5mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (5mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (5mi).
Herndon, West Virginia, USA
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