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
A mild shift in the average high-temperature occurs in September, reducing from a moderately hot 81.9°F (27.7°C) in August to a still warm 74.8°F (23.8°C). In Williamson, the expected average low-temperature for September is a refreshing 55.6°F (13.1°C).Humidity
In September, the average relative humidity is 78%.Rainfall
In September, the rain falls for 14.1 days. Throughout September, 1.97" (50mm) of precipitation is accumulated. In Williamson, during the entire year, the rain falls for 161.8 days and collects up to 28.07" (713mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
In September, the average length of the day is 12h and 26min.On the first day of September, sunrise is at 6:39 am and sunset at 7:42 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:54 pm EDT.
Sunshine
In Williamson, the average sunshine in September is 8.6h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for the average person.Note: In September, a regular UV index of 4 translates into these guidelines:
Put precautions into practice - Ensuring skin and eye safety is a necessity. During midday, the Sun's radiation is strongest, and it's advisable to reduce direct exposure. Loose clothes with a tight weave are optimal for safeguarding yourself against the Sun's rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow in Williamson?
Does it snow in September?
How many hours of daylight does Williamson have in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Williamson have in September?
What is the UV index reading in September?
Average temperature in September
Williamson, PA
- Average high temperature in September: 74.8°F
The warmest month (with the highest average high temperature) is July (84.4°F).
The month with the lowest average high temperature is January (35.4°F).
- Average low temperature in September: 55.6°F
The month with the highest average low temperature is July (62.6°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).
Average pressure in September
Williamson, PA
- Average pressure in September: 30.06"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
Williamson, PA
- Average wind speed in September: 5mph
The windiest month (with the highest average wind speed) is January (7.7mph).
The calmest months (with the lowest average wind speed) are July and August (4.5mph).
Average humidity in September
Williamson, PA
- Average humidity in September: 78%
The months with the highest relative humidity are February, May, October and December (79%).
The months with the lowest relative humidity are April and July (75%).
Average rainfall in September
Williamson, PA
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is May (3.15").
The driest month (with the least rainfall) is January (1.85").
Average rainfall days in September
Williamson, PA
- Average rainfall days in September: 14.1 days
The month with the highest number of rainy days is May (18.8 days).
The month with the least rainy days is November (9 days).
Average snowfall in September
Williamson, PA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.53").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Williamson, PA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (8.1 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
Williamson, PA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).
Average sunshine days in September
Williamson, PA
- Average sunshine days in September: 14.4 days
The month with the most sunshine days is November (18.5 days).
The month with the least sunshine days is May (10.4 days).
Average UV index in September
Williamson, PA
- Average UV index in September: 4
The months with the highest UV index are May, June and July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Williamson, PA
- Average cloud cover in September: 38
The months with the most cloud cover are January, February and December (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in September
Williamson, PA
- Average visibility in September: 5mi
The months with the highest visibility are April, June, July, August and November (6mi).
The months with the lowest visibility are January, February, March, May, September, October and December (5mi).
Williamson, Pennsylvania, USA
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