September weather forecast
Williamsport, PA

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Weather in September

September signals the onset of autumn in Williamsport. Waning summer warmth leaves the climate pleasant, with an average temperature high of 72.1°F (22.3°C) during the day. This month marks a visible shift in the weather pattern as daylight hours start to shrink. The receding daylight is an indicator of the forthcoming cooler months. With less cloud cover during the day, the city savors soothing autumnal hues under increasingly clear skies.

Temperature

The average high-temperature in Williamsport shows a slight dip in September, from August's moderately hot 79.2°F (26.2°C) to an agreeable 72.1°F (22.3°C). In Williamsport, the September nights cool down to an average low of 51.4°F (10.8°C).

Humidity

The average relative humidity in September in Williamsport is 81%.

Rainfall

In Williamsport, in September, it is raining for 11.2 days, with typically 1.38" (35mm) of accumulated precipitation. Throughout the year, in Williamsport, there are 145.2 rainfall days, and 16.57" (421mm) of precipitation is accumulated.

Snowfall

In Williamsport, snow does not fall in May through September.

Daylight

In September, the average length of the day is 12h and 28min.
On the first day of the month, sunrise is at 6:35 am and sunset at 7:40 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:51 pm EDT.

Sunshine

The average sunshine in September in Williamsport, Pennsylvania, is 8.6h.

UV index

The average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for average individuals.
Note: The daily high UV index of 3 in September translates into this advice:
Put precautions into practice - Protective measures against sun-induced damage are advised. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. Tightly woven clothing, when worn loosely, shields effectively against the Sun.
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Frequently asked questions

What are the temperatures in Williamsport in September?

In Williamsport, 72.1°F (22.3°C) is the average high-temperature and 51.4°F (10.8°C) is the average low-temperature during September. The average heat index (a.k.a. 'feels like', 'real feel'), which factors the actual air temperature with the relative humidity, in July is estimated at 87.8°F (31°C).

What is the average humidity in September in Williamsport?

In September, the average relative humidity in Williamsport, Pennsylvania, is 81%.

How much does it rain in Williamsport in September?

In Williamsport, Pennsylvania, in September, during 11.2 rainfall days, 1.38" (35mm) of precipitation is typically accumulated.

When it does not snow in Williamsport?

May through September are months without snowfall.

Does it snow in Williamsport in September?

In Williamsport, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Williamsport have in September?

The average day length in September in Williamsport is 12h and 28min.

What time are sunrise and sunset in September in Williamsport?

On the first day of September in Williamsport, Pennsylvania, sunrise is at 6:35 am and sunset at 7:40 pm. On the last day of the month, sunrise is at 7:04 am and sunset at 6:51 pm EDT.

How many hours of sunshine does Williamsport have in September?

In September, the average sunshine duration is 8.6h.

What is the UV index reading in September in Williamsport?

In September, the average daily maximum UV index in Williamsport is 3. A UV Index reading of 3 to 5 represents a medium hazard to health from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Williamsport, PA

Average temperature in September - Williamsport, PA
  • Average high temperature in September: 72.1°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (30.6°F).

  • Average low temperature in September: 51.4°F

The month with the highest average low temperature is July (59.2°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).

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Average pressure in September
Williamsport, PA

Average pressure in September - Williamsport, PA
  • Average pressure in September: 30.07"Hg

The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

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Average wind speed in September
Williamsport, PA

Average wind speed in September - Williamsport, PA
  • Average wind speed in September: 5.3mph

The windiest months (with the highest average wind speed) are January, March and April (7.5mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).

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Average humidity in September
Williamsport, PA

Average humidity in September - Williamsport, PA
  • Average humidity in September: 81%

The month with the highest relative humidity is February (84%).
The months with the lowest relative humidity are April and July (77%).

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Average rainfall in September
Williamsport, PA

Average rainfall in September - Williamsport, PA
  • Average rainfall in September: 1.38"

The wettest month (with the highest rainfall) is April (1.93").
The driest month (with the least rainfall) is November (0.94").

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Average rainfall days in September
Williamsport, PA

Average rainfall days in September - Williamsport, PA
  • Average rainfall days in September: 11.2 days

The month with the highest number of rainy days is May (16.6 days).
The month with the least rainy days is February (7.5 days).

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Average snowfall in September
Williamsport, PA

Average snowfall in September - Williamsport, PA
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.28").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in September
Williamsport, PA

Average snowfall days in September - Williamsport, PA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in September /
Average sunshine in September
Williamsport, PA

Average daylight in September / Average sunshine in September - Williamsport, PA
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in September: 8h and 4min

The month with the most sunshine is July (Average sunshine: 10h and 6min).
The months with the least sunshine are January and February (Average sunshine: 3h and 42min).

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Average sunshine days in September
Williamsport, PA

Average sunshine days in September - Williamsport, PA
  • Average sunshine days in September: 16.8 days

The month with the most sunshine days is November (18.7 days).
The month with the least sunshine days is May (11.8 days).

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Average UV index in September
Williamsport, PA

Average UV index in September - Williamsport, PA
  • Average UV index in September: 3

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).

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Average cloud cover in September
Williamsport, PA

Average cloud cover in September - Williamsport, PA
  • Average cloud cover in September: 41

The months with the most cloud cover are January and February (Cloud cover 60).
The month with the least cloud cover is July (Cloud cover 35).

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Average visibility in September
Williamsport, PA

Average visibility in September - Williamsport, PA
  • Average visibility in September: 4mi

The month with the highest visibility is April (6mi).
The month with the lowest visibility is September (4mi).

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Williamsport, Pennsylvania, USA

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