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September Weather in Harrisburg, United States

Last updated: June 24, 2025

In September, the average temperature in Harrisburg, United States is a pleasant 18°C (65°F). However, temperatures can vary significantly, with minimums dipping to 3°C (38°F) and soaring to a maximum of 33°C (91°F). Expect 107 mm (4.2 in) of precipitation spread over approximately 9 days, contributing to an average humidity level of 75%.

September Temperature in Harrisburg

In September in Harrisburg, the average temperature is 18°C (65°F). Maximum temperatures can reach 33°C (91°F), while minimums can drop as low as 3°C (38°F). This climate makes Harrisburg a great destination for travelers seeking a mix of warm days and cool evenings.

September Weather in Harrisburg: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Harrisburg, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Harrisburg, September typically has an average temperature of 18°C (65°F), with highs reaching up to 33°C (91°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec202035455973757165483526
Data source: Temperature data for Harrisburg generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Harrisburg

In Harrisburg in September, the precipitation amount is 107 mm (4.2 in), occurring over a span of 9 days.

September Precipitation Trends in Harrisburg

The chart displays monthly precipitation patterns in Harrisburg, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Harrisburg, September typically receives around 107 mm (4.2 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec22246582128857794107792539
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Harrisburg

In Harrisburg in September, humidity is 75%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket that can make outdoor exploration feel a bit stifling, potentially leading to discomfort during travel activities.

September Average Humidity in Harrisburg

This chart illustrates the average monthly humidity levels in Harrisburg, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Harrisburg is approximately 75%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec80%84%75%79%74%81%82%80%75%77%85%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Harrisburg

In Harrisburg in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Harrisburg.

Maximum UV Index Levels in Harrisburg for September

The chart shows the monthly maximum UV Index (UVI) for Harrisburg in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Harrisburg typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec25589111098532
Data source: Harrisburg September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Harrisburg Compares to Other Months

Weather in Harrisburg varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Harrisburg, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Harrisburg, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-7°C (20°F)21 mm (0.8 inches)80%low
February Weather-7°C (20°F)24 mm (0.9 inches)84%moderate
March Weather2°C (35°F)65 mm (2.6 inches)75%moderate
April Weather7°C (45°F)82 mm (3.2 inches)79%very high
May Weather15°C (59°F)128 mm (5.0 inches)74%very high
June Weather23°C (73°F)85 mm (3.3 inches)81%extreme
July Weather24°C (75°F)77 mm (3.0 inches)82%very high
August Weather22°C (72°F)94 mm (3.7 inches)80%very high
September Weather18°C (65°F)107 mm (4.2 inches)75%very high
October Weather9°C (48°F)79 mm (3.1 inches)77%moderate
November Weather1°C (35°F)25 mm (1.0 inches)85%moderate
December Weather-3°C (26°F)39 mm (1.5 inches)83%low

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