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 September, the meteorological conditions change slightly, with the average high-temperature moving from a warm 83.3°F (28.5°C) in August to a still moderately hot 76.5°F (24.7°C). September's average low-temperature reading settles at a refreshing 61.2°F (16.2°C).Humidity
The average relative humidity in September is 77%.Rainfall
The month with the least rainfall in Williamstown is September, when the rain falls for 12 days and typically collects 1.73" (44mm) of precipitation.Snowfall
In Williamstown, snow does not fall in June through October.Daylight
The average length of the day in September is 12h and 26min.On the first day of September in Williamstown, sunrise is at 6:28 am and sunset at 7:30 pm. On the last day of the month, sunrise is at 6:55 am and sunset at 6:43 pm EDT.
Sunshine
In Williamstown, the average sunshine in September is 9.1h.UV index
The average daily maximum UV index in September in Williamstown is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: A maximum high daily UV index of 5 during September translates into the following directions:
Be vigilant - A duty to shield skin and eyes from injury exists. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September in Williamstown?
What is the average humidity in September in Williamstown?
What is the driest month in Williamstown?
How much does it rain in Williamstown in September?
When it does not snow in Williamstown?
How many hours of daylight does Williamstown have in September?
What time are sunrise and sunset in September in Williamstown?
How long on average sun shines in September in Williamstown?
What is the UV index reading in September in Williamstown?
Average temperature in September
Williamstown, NJ
- Average high temperature in September: 76.5°F
The warmest month (with the highest average high temperature) is July (85.3°F).
The month with the lowest average high temperature is January (38.1°F).
- Average low temperature in September: 61.2°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.8°F).
Average pressure in September
Williamstown, NJ
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed in September
Williamstown, NJ
- Average wind speed in September: 6.2mph
The windiest month (with the highest average wind speed) is April (8.7mph).
The calmest month (with the lowest average wind speed) is August (5.7mph).
Average humidity in September
Williamstown, NJ
- Average humidity in September: 77%
The month with the highest relative humidity is October (78%).
The month with the lowest relative humidity is April (71%).
Average rainfall in September
Williamstown, NJ
- Average rainfall in September: 1.73"
The wettest month (with the highest rainfall) is December (3.35").
The driest month (with the least rainfall) is September (1.73").
Average rainfall days in September
Williamstown, NJ
- Average rainfall days in September: 12 days
The month with the highest number of rainy days is July (16.9 days).
The month with the least rainy days is January (8.8 days).
Average snowfall in September
Williamstown, NJ
- Average snowfall in September: 0"
The month with the highest snowfall is March (3.54").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Williamstown, NJ
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.5 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Williamstown, NJ
- 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 24min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 4h and 54min).
Average sunshine days in September
Williamstown, NJ
- Average sunshine days in September: 16.3 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (11.8 days).
Average UV index in September
Williamstown, NJ
- 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
Williamstown, NJ
- Average cloud cover in September: 35
The months with the most cloud cover are February and March (Cloud cover 46).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in September
Williamstown, NJ
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Williamstown, New Jersey, USA
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