September weather forecast
Pennsylvania, USA

As September unfolds in Pennsylvania, it marks the onset of autumn, introducing a refreshing blend of summer warmth and the crispness of fall. Temperatures typically range from 52°F (11.1°C) to 75°F (23.9°C), with the latter part of the month witnessing a more noticeable drop in temperatures. While daytime remains comfortably warm, evenings and early mornings take on a cooler persona, capturing the essence of fall.

September also ushers in the eagerly anticipated fall foliage. The state's landscapes transform with hues of amber, gold, and ruby, offering visually stunning panoramas, especially in the mountainous regions. Rainfall becomes less frequent, and when it does occur, it’s often lighter and more sporadic compared to the summer months. The drier climate, combined with the decreasing temperatures, sets the stage for the array of autumn festivals and outdoor events that the state is renowned for.

Areas close to Lake Erie, while experiencing the cooling trend, remain relatively milder, making them ideal for late summer beach visits or lakeside activities. In contrast, the higher altitudes, especially in the Appalachian region, showcase an earlier onset of fall colors, combined with slightly cooler temperatures.

In comparison to August, September is distinctively autumnal. While the former transitions from summer's peak to its decline, September embraces the fall spirit wholeheartedly. The days grow shorter, nights become crisper, and there's a general sense of transition as Pennsylvania prepares for the cooler months ahead. It's a month that offers a harmonious blend of the residual warmth of summer and the refreshing beginnings of autumn.

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• Philadelphia - September »
  In Philadelphia in September, it is raining for 10.5 days, with typically 0.87" (22mm) of accumulated precipitation. In Philadelphia, in September, it is raining for 10.5 days, with typically 0.87" (22mm) of accumulated precipitation.
• Pittsburgh - September »
  On the first day of September in Pittsburgh sunrise is at 6:48 am and sunset at 7:51 pm. September in Pittsburgh greets autumn with open arms, showcasing a steady decrease in temperatures, resulting in comfortable, moderate weather.
• Allentown - September »
  The month with the least rainfall in Allentown is September, when the rain falls for 11.5 days and typically collects 1.61" (41mm) of precipitation. In Allentown, during September, the rain falls for 11.5 days and regularly aggregates up to 1.61" (41mm) of precipitation.
• Erie - September »
  In Erie during September, the rain falls for 7.9 days and regularly aggregates up to 0.35" (9mm) of precipitation. In September, the average ocean temperature in Erie is 70°F (21.1°C).
• Reading - September »
  In Reading snow does not fall in June through September. September in Reading, Pennsylvania, highlights the turn of season with falling temperatures and reducing daylight hours.
• Scranton - September »
  The months with the least rainfall in Scranton are January and September Rain falls for 10.6 days and accumulates 1.38" (35mm) of rain. In Scranton snow does not fall in June through September.
• Bethlehem - September »
  On the first day of September in Bethlehem sunrise is at 6:29 am and sunset at 7:33 pm. In Bethlehem snow does not fall in June through September.
• Lancaster - September »
  February and September are months with the least rain in Lancaster when the rain falls for 12.2 days and typically aggregates up to 1.89" (48mm) of rain. In September, in Lancaster, the rain falls for 12.2 days.
• Harrisburg - September »
  On the first day of September in Harrisburg sunrise is at 6:35 am and sunset at 7:38 pm. In Harrisburg in September, during 9.7 rainfall days, 0.79" (20mm) of precipitation is typically accumulated.
• Altoona - September »
  In Altoona in September, it is raining for 13.5 days, with typically 1.81" (46mm) of accumulated precipitation. In Altoona the average relative humidity in September is 80%.
• York - September »
  In York snow does not fall in May through September. In York, during September, the rain falls for 10.5 days and regularly aggregates up to 1.22" (31mm) of precipitation.
• State College - September »
  In State College, Pennsylvania, in September, it is raining for 13.8 days, with typically 2.24" (57mm) of accumulated precipitation. In State College, Pennsylvania, snow does not fall in June through September.