September weather forecastWilliamstown, WV
September
Weather in September
September ushers in a noticeable cooling trend as temperatures oscillate from 56.7°F (13.7°C) to 77.9°F (25.5°C), signaling the onset of fall in Williamstown, West Virginia. Contrary to the falling temperatures, the rainfall experiences a slight dip to 1.46" (37mm). This period is characterized by shorter daylight hours, enhanced visibility, and dramatic leaf colors. Moving towards October, temperatures drop further, paving the way for the crisp autumn air.Temperature
September is characterized by a mild reduction in the average high-temperature, from 84.2°F (29°C) in August to a still warm 77.9°F (25.5°C). September nights in Williamstown experience a consistent temperature drop to a mild 56.7°F (13.7°C).Humidity
In September, the average relative humidity is 77%.Rainfall
The month with the least rainfall in Williamstown, West Virginia, is September, when the rain falls for 12.5 days and typically collects 1.46" (37mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
The average length of the day in September is 12h and 26min.On the first day of September in Williamstown, sunrise is at 6:54 am and sunset at 7:56 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 7:09 pm EDT.
Sunshine
In Williamstown, West Virginia, the average sunshine in September is 8.3h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from unsafe exposure to UV radiation for the average person.Note: The daily high UV index of 4 during September translates into the following recommendations:
Undertake precautions - It is suggested to shield oneself from sunburn. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. 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
Average temperature in September
Williamstown, WV
- Average high temperature in September: 77.9°F
The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (36.1°F).
- Average low temperature in September: 56.7°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (22.8°F).
Average pressure in September
Williamstown, WV
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.96"Hg).
Average wind speed in September
Williamstown, WV
- Average wind speed in September: 4.7mph
The windiest month (with the highest average wind speed) is February (6.8mph).
The calmest month (with the lowest average wind speed) is August (4.2mph).
Average humidity in September
Williamstown, WV
- Average humidity in September: 77%
The months with the highest relative humidity are January and February (83%).
The months with the lowest relative humidity are June, July and August (76%).
Average rainfall in September
Williamstown, WV
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is May (3.19").
The driest month (with the least rainfall) is September (1.46").
Average rainfall days in September
Williamstown, WV
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is November (8.4 days).
Average snowfall in September
Williamstown, WV
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.8").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Williamstown, WV
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.5 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Williamstown, WV
- 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 24min).
- Average sunshine in September: 8h and 18min
The month with the most sunshine is August (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 24min).
Average sunshine days in September
Williamstown, WV
- Average sunshine days in September: 15.2 days
The month with the most sunshine days is November (19.9 days).
The month with the least sunshine days is May (9.8 days).
Average UV index in September
Williamstown, WV
- Average UV index in September: 4
The months with the highest UV index are 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
Williamstown, WV
- Average cloud cover in September: 38
The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is August (Cloud cover 34).
Average visibility in September
Williamstown, WV
- Average visibility in September: 5mi
The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).
