September Weather in Charleston, United States

Last updated: June 24, 2025

In Charleston, United States, the average temperature in September hovers around 21°C (71°F). Expect a minimum of 6°C (43°F) and a maximum of 33°C (92°F), making for quite a range! Moisture is in the air with an average humidity of 79%, accompanied by 67 mm (2.6 in) of precipitation over 6 days. Whether you're soaking in the warmth or bracing for a sudden shower, it's a month full of vibrant weather!

September Temperature in Charleston

In September in Charleston, the average temperature is 21°C (71°F), with maximums reaching 33°C (92°F) and minimums dropping to as low as 6°C (43°F), making it an ideal time for travelers to experience a pleasant climate and enjoy outdoor activities.

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

The chart illustrates September temperature patterns in Charleston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Charleston, September typically has an average temperature of 21°C (71°F), with highs reaching up to 33°C (92°F) and lows dropping to around 6°C (43°F).

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

September Precipitation in Charleston

In Charleston in September, the precipitation amount is 67 mm (2.6 in) over the course of 6 days.

September Precipitation Trends in Charleston

The chart displays monthly precipitation patterns in Charleston, 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 Charleston, September typically receives around 67 mm (2.6 inches) of precipitation spread over approximately 6 days.

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

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Millimeters (mm) Inches (in)

September Humidity in Charleston

In Charleston in September humidity is 79%. With an average temperature of 21°C (71°F), this humidity feels like a warm, sticky embrace that can make outdoor activities feel laborious and exhausting. Travelers should be prepared to hydrate frequently and take breaks in shaded areas to fully enjoy their time exploring.

September Average Humidity in Charleston

This chart illustrates the average monthly humidity levels in Charleston, 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 Charleston is approximately 79%, 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 Charleston

In Charleston 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 Charleston.

Maximum UV Index Levels in Charleston for September

The chart shows the monthly maximum UV Index (UVI) for Charleston 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 Charleston typically reaches 8, which falls under the very high exposure category.

Data source: Charleston 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 Charleston Compares to Other Months

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

This table compares monthly weather conditions in Charleston, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-1°C (30°F)	78 mm (3.1 inches)	84%	moderate
February Weather	1°C (33°F)	79 mm (3.1 inches)	82%	moderate
March Weather	7°C (44°F)	125 mm (4.9 inches)	84%	high
April Weather	12°C (53°F)	117 mm (4.6 inches)	83%	very high
May Weather	19°C (66°F)	135 mm (5.3 inches)	80%	very high
June Weather	24°C (76°F)	110 mm (4.3 inches)	83%	extreme
July Weather	25°C (78°F)	116 mm (4.6 inches)	82%	very high
August Weather	24°C (75°F)	123 mm (4.8 inches)	82%	very high
September Weather	21°C (71°F)	67 mm (2.6 inches)	79%	very high
October Weather	14°C (58°F)	115 mm (4.5 inches)	79%	high
November Weather	6°C (42°F)	89 mm (3.5 inches)	88%	moderate
December Weather	3°C (37°F)	65 mm (2.6 inches)	87%	moderate