Allentown
Pennsylvania, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Allentown, PA

An aerial view of the vast city of Allentown in Pennsylvania, on a hot, sunny day, with the partly cloudy sky and a far view of a clear horizon line
An aerial view of the vast city of Allentown in Pennsylvania, on a hot, sunny day, with the partly cloudy sky and a far view of a clear horizon line
September, the first month of the autumn, in Allentown, is still a warm month, with temperature in the range of an average high of 74.8°F (23.8°C) and an average low of 52.9°F (11.6°C).

Temperature

In September, the average high-temperature slightly decreases, from 82.4°F (28°C) in August, to a still moderately hot 74.8°F (23.8°C). In September, in Allentown, the average low-temperature is 52.9°F (11.6°C).

Humidity

With an average relative humidity of 74%, September is the most humid month in Allentown, Pennsylvania.

Rainfall

In Allentown, it is raining for 9.1 days, with typically 4.6" (117.3mm) of accumulated precipitation. In Allentown, during the entire year, the rain falls for 126.8 days and collects up to 45.4" (1151.9mm) of precipitation.

Snowfall

In Allentown, during the entire year, snow aggregates up to 32.9" (835.7mm).

Daylight

In Allentown, the average length of the day in September is 12.4h.

Sunshine

The average sunshine in Allentown is 7h.

UV index

In Allentown, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health hazard from the exposure to the Sun's UV rays for ordinary individuals.
In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.

What is the temperature in September in Allentown?

In Allentown, Pennsylvania, in September, the average high-temperature is 74.8°F (23.8°C), and the average low-temperature is 52.9°F (11.6°C).

What is the most humid month in Allentown?

September is the most humid month, with an average relative humidity of 74%.

What is the average humidity in September in Allentown?

In Allentown, the average relative humidity in September is 74%.

How much does it rain in Allentown in September?

In Allentown, Pennsylvania, in September, it is raining for 9.1 days, with typically 4.6" (117.3mm) of accumulated precipitation.

What is the average length of the day in September in Allentown?

In Allentown, the average length of the day in September is 12.4h.

How many hours of sunshine does Allentown have in September?

The average sunshine in September in Allentown is 7h.

What is the UV index intensity in September in Allentown?

In Allentown, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from unsafe exposure to the Sun's UV rays.
Average temperature in September - Allentown, PA
  • Average high temperature in September: 74.9°F

The warmest month (with the highest average high temperature) is July (84.2°F).
The month with the lowest average high temperature is January (36°F).

  • Average low temperature in September: 52.9°F

The month with the highest average low temperature is July (62.7°F).
The coldest month (with the lowest average low temperature) is January (19.5°F).

Average humidity in September - Allentown, PA
  • Average humidity in September: 74%

The month with the highest relative humidity is September (74%).
The month with the lowest relative humidity is April (60.9%).

Average rainfall in September - Allentown, PA
  • Average rainfall in September: 4.6"

The wettest month (with the highest rainfall) is July (5").
The driest month (with the lowest rainfall) is February (2.7").

Average rainfall days in September - Allentown, PA
  • Average rainfall days in September: 9.1 days

Months with the highest number of rainy days are April and May (12.1 days).
Months with the lowest number of rainy days are September and October (9.1 days).

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

The month with the highest snowfall is February (11.1").
Months with the lowest snowfall are May, June, July, August, September and October (0").

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

The month with the highest number of snowfall days is January (5.6 days).
Months with the lowest number of snowfall days are May, June, July, August, September and October (0 days).

Average daylight in September / Average sunshine in September - Allentown, PA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 15h).
The month with shortest days is December (Average daylight: 9.3h).

  • Average sunshine in September: 7h

Months with most sunshine are June and July (Average sunshine: 9h).
Months with least sunshine are November and December (Average sunshine: 4).

Average UV index in September - Allentown, PA
  • Average UV index in September: 6

Months with the highest UV index are June and July (UV index 9).
The month with the lowest UV index is December (UV index 1).