Williamsport (PA)
September
Weather in Williamsport, Pennsylvania for September 2026
Your guide to Williamsport weather in September - trends and predictions
So far, September 2026 in Williamsport is slightly warmer than the historical average by 1.7 °F.
The forecast for the next days in Williamsport predicts temperatures to be around 17 °F, close to the historical average.
In general, the average temperature in Williamsport at the beginning of September is 24.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 17 °F by the end of September.
Williamsport experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 120.8 mm.
New! Chat with our AI weatherman - it’s amazing and free.
Temperatures
Rain 🌧️
More
20
Dry days
10
Rainy days
0
Snow days
22°/12°
Temperatures
10 km/h
Avg max wind
78 %
Avg humidity
Williamsport Weather September
Move between months or click on a day
Temperatures trend during September in Williamsport
See the weather trend as well as the moving average line
September weather in Williamsport day by day
Click on a date for more information
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Fog | 28° /15° | 0.1 mm | 6 | |
| Sept. 2 | Mist | 24° /13° | 6.5 mm | 4 | |
| Sept. 3 |  Sunny | 25° /11° | 107 mm | 4 | |
| Sept. 4 | Sunny | 25° /14° | 4.5 mm | 5 | |
| Sept. 5 | Mist | 24° /13° | 0 mm | 6 | |
| Sept. 6 | Fog | 24° /13° | 0.1 mm | 6 | |
| Sept. 7 |  Moderate rain | 20° /10° | 3 mm | 5 | |
| Sept. 8 | Fog | 21° /7° | 0 mm | 5 | |
| Sept. 9 |  Partly cloudy | 25° /9° | 0.5 mm | 5 | |
| Sept. 10 | Partly cloudy | 25° /12° | 5.7 mm | 5 | |
| Sept. 11 | Mist | 25° /11° | 0 mm | 6 | |
| Sept. 12 | Mist | 25° /11° | 0.4 mm | 4 | |
| Sept. 13 | Mist | 26° /13° | 6.2 mm | 4 | |
| Sept. 14 | Mist | 25° /13° | 0.1 mm | 6 | |
| Sept. 15 | Mist | 25° /11° | 0 mm | 6 | |
| Sept. 16 | Mist | 25° /13° | 0.1 mm | 5 | |
| Sept. 17 |  Cloudy | 24° /14° | 2 mm | 4 | |
| Sept. 18 | Fog | 25° /14° | 0.5 mm | 5 | |
| Sept. 19 |  Overcast | 21° /11° | 0 mm | 6.4 | |
| Sept. 20 | Fog | 18° /14° | 13.5 mm | 0.5 | |
| Sept. 21 | Mist | 20° /12° | 2.7 mm | 3.7 | |
| Sept. 22 |  Light rain shower | 13° /10° | 11.8 mm | 3 | |
| Sept. 23 | Light rain shower | 10° /8° | 7 mm | 2 | |
| Sept. 24 | Light rain shower | 11° /9° | 9.3 mm | 3 | |
| Sept. 25 | Mist | 12° /10° | 4.3 mm | 3 | |
| Sept. 26 | Sunny | 19° /7° | 0 mm | 5 | |
| Sept. 27 | Sunny | 18° /8° | 0 mm | 5 | |
| Sept. 28 | Partly cloudy | 20° /7° | 0 mm | 5 | |
| Sept. 29 | Sunny | 21° /8° | 0 mm | 6 | |
| Sept. 30 | Overcast | 18° /10° | 0 mm | 4 | |
| Next | |||||
Important Notice
Our weather forecast for Williamsport 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 Williamsport forecast closer to your planned date for the most up-to-date weather information.
Change Month
Williamsport in September - FAQ
What are the expected maximum and minimum temperatures in Williamsport during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 12°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Williamsport during September?
Significant rainfall exceeding 120.8 mm is expected in Williamsport during September, occurring over more than 10 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Williamsport during September?
The average wind speed in Williamsport during September is 10 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Williamsport
Explore the daily rainfall trends and prepare for Williamsports September weather 💧
Typically, Williamsport has 10 rainy days in September with a total of 120.8 mm of rainfall.
UV exposure in Williamsport during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Quick links
More Williamsport weather pages
You are here
Where is Williamsport?Get accurate weather forecasts for Williamsport, located at latitude 41.241 and longitude -77.001. Stay updated with localized weather information tailored for Williamsport.
Found a mistake?
We appreciate your attention to details. Tell us here.