Allentown (PA)
September
Weather in Allentown, Pennsylvania for September 2025
Your guide to Allentown weather in September - trends and predictions
In general, the average temperature in Allentown at the beginning of September is 23.7 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19.6 °F by the end of September.
The climate of Allentown in September is notably wet, with an average of 11 rainy days, and a total of 74.3 mm of precipitation.
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Temperatures
Rain 🌧️
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19
Dry days
11
Rainy days
0
Snow days
23°/13°
Temperatures
15 km/h
Avg max wind
75 %
Avg humidity
Allentown Weather September
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Temperatures trend during September in Allentown
See the weather trend as well as the moving average line
September weather in Allentown day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Moderate or heavy rain shower | 27° /19° | 5.4 mm | 6 | |
| Sept. 2 |  Overcast | 23° /14° | 0 mm | 5 | |
| Sept. 3 |  Sunny | 23° /8° | 0 mm | 6 | |
| Sept. 4 | Sunny | 23° /9° | 0 mm | 6 | |
| Sept. 5 | Sunny | 25° /10° | 0 mm | 7 | |
| Sept. 6 | Overcast | 24° /12° | 0 mm | 5 | |
| Sept. 7 | Moderate or heavy rain shower | 21° /12° | 9.3 mm | 5 | |
| Sept. 8 | Sunny | 20° /8° | 0 mm | 6 | |
| Sept. 9 |  Partly cloudy | 24° /8° | 0 mm | 6 | |
| Sept. 10 | Sunny | 25° /11° | 0 mm | 7 | |
| Sept. 11 | Sunny | 27° /10° | 0 mm | 7 | |
| Sept. 12 | Sunny | 26° /12° | 0 mm | 7 | |
| Sept. 13 | Sunny | 27° /12° | 0 mm | 7 | |
| Sept. 14 | Partly cloudy | 28° /13° | 0 mm | 7 | |
| Sept. 15 | Partly cloudy | 28° /13° | 0 mm | 7 | |
| Sept. 16 | Overcast | 24° /12° | 0 mm | 5 | |
| Sept. 17 | Overcast | 24° /14° | 0 mm | 5 | |
| Sept. 18 |  Patchy rain possible | 22° /16° | 0.4 mm | 5 | |
| Sept. 19 | Overcast | 27° /16° | 7.4 mm | 6 | |
| Sept. 20 | Overcast | 24° /16° | 0 mm | 5 | |
| Sept. 21 | Overcast | 24° /17° | 0 mm | 5 | |
| Sept. 22 | Overcast | 21° /14° | 0 mm | 5 | |
| Sept. 23 | Moderate or heavy rain shower | 18° /13° | 9.8 mm | 4 | |
| Sept. 24 | Overcast | 20° /15° | 3.7 mm | 5 | |
| Sept. 25 | Moderate or heavy rain shower | 18° /16° | 11.7 mm | 4 | |
| Sept. 26 | Moderate rain at times | 25° /18° | 16.2 mm | 6 | |
| Sept. 27 | Moderate or heavy rain shower | 20° /16° | 5.1 mm | 5 | |
| Sept. 28 | Moderate rain at times | 19° /16° | 4.7 mm | 4 | |
| Sept. 29 | Patchy rain possible | 17° /15° | 0.6 mm | 4 | |
| Sept. 30 |  Mist | 18° /14° | 0 mm | 4 | |
| Next | |||||
Important Notice
Our weather forecast for Allentown in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Allentown forecast closer to your planned date for the most up-to-date weather information.
Change Month
Allentown in September - FAQ
What are the expected maximum and minimum temperatures in Allentown during September?
Enjoy moderate daytime temperatures of up to 23° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Allentown during September?
Moderate rainfall is anticipated in Allentown during September, with a total of 74.3 mm spread over approximately 11 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Allentown during September?
The average wind speed in Allentown during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Allentown
Explore the daily rainfall trends and prepare for Allentowns September weather 💧
UV exposure in Allentown during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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