September weather forecast
West Chester, PA

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A cool summer day over the colorful cityscape of West Chester, Pennsylvania
A cool summer day over the colorful cityscape of West Chester, Pennsylvania

Weather in September

September arrives in West Chester, gently transitioning the city from the sizzle of summer to the coolness of fall. The weather in this month embodies the very essence of a city on the brink of change: the recorded average temperatures have a notable decrease, paving the way for an autumnal breeze. Leaves start displaying their fiery hues, capturing the hearts of locals and visitors alike. The city's parks and gardens enter a slower phase, preluding the spectacular autumnal transition. The blend of crisp air, vibrant foliage, and soft sunlight make September a visually appealing and temperate month.

Temperature

West Chester in September undergoes a slight reduction in the average high-temperature, shifting from August's warm 82.4°F (28°C) to a still moderately hot 75.7°F (24.3°C). Throughout September, an average nighttime temperature of 59.2°F (15.1°C) is experienced.

Humidity

The average relative humidity in September is 77%.

Rainfall

In West Chester, in September, it is raining for 11.5 days, with typically 1.1" (28mm) of accumulated precipitation. Throughout the year, in West Chester, Pennsylvania, there are 128.5 rainfall days, and 14.92" (379mm) of precipitation is accumulated.

Snowfall

In West Chester, snow does not fall in June through October.

Daylight

In September, the average length of the day is 12h and 26min.
On the first day of September, sunrise is at 6:30 am and sunset at 7:33 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:45 pm EDT.

Sunshine

In West Chester, the average sunshine in September is 8.6h.

UV index

In September, the average daily maximum UV index in West Chester is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV rays for the ordinary person.
Note: During September, 4 as the daily maximum UV index converts into the following advice:
Exercise care. People with light skin might get burns in fewer than 30 minutes. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.
Updated: Aug 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for West Chester in September?

The high-temperature, in September, in West Chester, is 75.7°F (24.3°C), while the low-temperature averages to 59.2°F (15.1°C). In August, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 87.8°F (31°C).

What is the average humidity in September?

In West Chester, the average relative humidity in September is 77%.

How many days does it rain in September?

In West Chester, in September, during 11.5 rainfall days, 1.1" (28mm) of precipitation is typically accumulated.

When it does not snow?

June through October are months without snowfall.

How many hours of daylight does West Chester have in September?

In September, the average day length is 12h and 26min.

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:30 am and sunset at 7:33 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:45 pm EDT.

How long on average sun shines in September?

In September, the average sunshine duration in West Chester is 8.6h.

What is the UV index intensity in September?

In West Chester, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from unsafe exposure to Sun's UV rays.
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
West Chester, PA

Average temperature in September - West Chester, PA
  • Average high temperature in September: 75.7°F

The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is January (36.5°F).

  • Average low temperature in September: 59.2°F

The month with the highest average low temperature is July (67.1°F).
The coldest month (with the lowest average low temperature) is January (24.4°F).

Average pressure in September
West Chester, PA

Average pressure in September - West Chester, PA
  • Average pressure in September: 30.06"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
West Chester, PA

Average wind speed in September - West Chester, PA
  • Average wind speed in September: 5.7mph

The windiest month (with the highest average wind speed) is March (8.6mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).

Average humidity in September
West Chester, PA

Average humidity in September - West Chester, PA
  • Average humidity in September: 77%

The months with the highest relative humidity are February and October (79%).
The month with the lowest relative humidity is April (73%).

Average rainfall in September
West Chester, PA

Average rainfall in September - West Chester, PA
  • Average rainfall in September: 1.1"

The wettest month (with the highest rainfall) is August (2.01").
The driest month (with the least rainfall) is January (0.83").

Average rainfall days in September
West Chester, PA

Average rainfall days in September - West Chester, PA
  • Average rainfall days in September: 11.5 days

The month with the highest number of rainy days is July (15.3 days).
The month with the least rainy days is January (5.7 days).

Average snowfall in September
West Chester, PA

Average snowfall in September - West Chester, PA
  • Average snowfall in September: 0"

The month with the highest snowfall is March (1.54").
The months with the least snowfall are June, July, August, September and October (0").

Average snowfall days in September
West Chester, PA

Average snowfall days in September - West Chester, PA
  • 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
West Chester, PA

Average daylight in September / Average sunshine in September - West Chester, 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 36min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

Average sunshine days in September
West Chester, PA

Average sunshine days in September - West Chester, PA
  • Average sunshine days in September: 17 days

The month with the most sunshine days is November (21.7 days).
The month with the least sunshine days is August (13.1 days).

Average UV index in September
West Chester, PA

Average UV index in September - West Chester, PA
  • Average UV index in September: 4

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, March, November and December (UV index 2).

Average cloud cover in September
West Chester, PA

Average cloud cover in September - West Chester, PA
  • Average cloud cover in September: 39

The month with the most cloud cover is February (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 32).

Average visibility in September
West Chester, PA

Average visibility in September - West Chester, PA
  • Average visibility in September: 5mi

The months with the highest visibility are January, February, March, April, June, July, August, October, November and December (6mi).
The months with the lowest visibility are May and September (5mi).

West Chester, Pennsylvania, USA

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