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's arrival coincides with a soft drop in the average high-temperature, subtly decreasing from August's 81.3°F (27.4°C) to a still moderately hot 75.7°F (24.3°C). In the month of September, the nighttime temperature dips to a steady average of 58.1°F (14.5°C).Humidity
The average relative humidity in September in Williamstown is 77%.Rainfall
September is the month with the least rainfall. Rain falls for 13.7 days and accumulates 1.97" (50mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
In Williamstown, the average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 7:10 am and sunset at 8:12 pm. On the last day of the month, sunrise is at 7:37 am and sunset at 7:25 pm EDT.
Sunshine
In September, the average sunshine is 8.2h.UV index
The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: The daily high UV index of 5 during September translates into the following recommendations:
Stay alert. Light-skinned people could suffer burns in less than 30 minutes. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Williamstown in September?
What is the average humidity in September?
What is the driest month?
How many days does it rain in September?
When it does not snow in Williamstown?
Does it snow in September?
How many hours of daylight does Williamstown have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Williamstown have in September?
What is the UV index reading in September?
Average temperature in September
Williamstown, IN
- Average high temperature in September: 75.7°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (34.7°F).
- Average low temperature in September: 58.1°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (21.9°F).
Average pressure in September
Williamstown, IN
- Average pressure in September: 30.03"Hg
The months with the highest atmospheric pressure are January and November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Williamstown, IN
- Average wind speed in September: 6.3mph
The windiest month (with the highest average wind speed) is January (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.6mph).
Average humidity in September
Williamstown, IN
- Average humidity in September: 77%
The months with the highest relative humidity are January and December (82%).
The month with the lowest relative humidity is October (74%).
Average rainfall in September
Williamstown, IN
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is May (3.78").
The driest month (with the least rainfall) is September (1.97").
Average rainfall days in September
Williamstown, IN
- Average rainfall days in September: 13.7 days
The month with the highest number of rainy days is May (19.3 days).
The month with the least rainy days is February (8.4 days).
Average snowfall in September
Williamstown, IN
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.64").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Williamstown, IN
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Williamstown, IN
- 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: 8h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in September
Williamstown, IN
- Average sunshine days in September: 14 days
The month with the most sunshine days is November (16.8 days).
The month with the least sunshine days is May (9.9 days).
Average UV index in September
Williamstown, IN
- Average UV index in September: 5
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Williamstown, IN
- Average cloud cover in September: 34
The month with the most cloud cover is January (Cloud cover 60).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in September
Williamstown, IN
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Williamstown, Indiana, USA
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