September Weather in Harrisburg, United States

Last updated: June 24, 2025

In September, the average temperature in Harrisburg, United States hovers around 19°C (66°F). However, be prepared for a temperature range that can dip to a chilly -1°C (30°F) and soar up to a sizzling 37°C (100°F). Expect 24 mm (1.0 in) of precipitation spread over 4 days, along with an average humidity level of 75%.

September Temperature in Harrisburg

In September, in Harrisburg, the average temperature is 19°C (66°F). Maximum temperatures can reach 37°C (100°F), and minimums can drop to as low as -1°C (30°F). Be sure to pack for a wide range of weather if you're traveling to Harrisburg this month!

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 19°C (66°F), with highs reaching up to 37°C (100°F) and lows dropping to around -1°C (30°F).

Data source: Temperature data for Harrisburg generated using information from the Copernicus Climate Change Service.

September Precipitation in Harrisburg

In Harrisburg in September, the precipitation amount is 24 mm (1.0 in) over the course of 4 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 24 mm (1.0 inches) of precipitation spread over approximately 4 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Harrisburg

In Harrisburg in September humidity is 75%. With an average temperature of 19°C (66°F), this humidity feels like a warm, enveloping blanket, making it slightly uncomfortable for traveling as you navigate through the thick, muggy air.

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.

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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check 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 9, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	0°C (32°F)	14 mm (0.6 inches)	72%	moderate
February Weather	-2°C (30°F)	23 mm (0.9 inches)	76%	moderate
March Weather	5°C (40°F)	67 mm (2.7 inches)	61%	high
April Weather	8°C (46°F)	53 mm (2.1 inches)	60%	very high
May Weather	13°C (55°F)	117 mm (4.6 inches)	74%	very high
June Weather	21°C (69°F)	57 mm (2.2 inches)	82%	extreme
July Weather	24°C (75°F)	46 mm (1.8 inches)	82%	extreme
August Weather	22°C (73°F)	35 mm (1.4 inches)	84%	very high
September Weather	19°C (66°F)	24 mm (1.0 inches)	75%	very high
October Weather	9°C (48°F)	36 mm (1.4 inches)	73%	high
November Weather	5°C (42°F)	25 mm (1.0 inches)	74%	moderate
December Weather	1°C (35°F)	18 mm (0.7 inches)	77%	moderate