September Weather in Charleston, United States

Last updated: June 24, 2025

In September, the average temperature in Charleston, United States hovers around 23°C (74°F). During this time, you can expect a minimum of 9°C (48°F) and a maximum of 36°C (96°F). Additionally, the area sees 85 mm (3.3 in) of precipitation over approximately 7 days, with an average humidity of 75%. Whether you’re planning outdoor activities or cozy indoor relaxation, be prepared for varying weather conditions!

September Temperature in Charleston

In September in Charleston, the average temperature is 23°C (74°F). The maximum can reach 36°C (96°F), while the minimum can be as low as 9°C (48°F). It's a perfect time for travelers to experience pleasant weather, making outdoor activities enjoyable.

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 23°C (74°F), with highs reaching up to 36°C (96°F) and lows dropping to around 9°C (48°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 total precipitation amount is 85 mm (3.3 in) over the course of 7 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 85 mm (3.3 inches) of precipitation spread over approximately 7 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 Charleston

In Charleston in September, humidity is 75%. With an average temperature of 23°C (74°F), this humidity feels like a warm, heavy blanket wrapping around you, making it feel more sweltering than it actually is, which can be quite uncomfortable for traveling.

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 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 Charleston

In Charleston 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 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 9, 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	3°C (38°F)	110 mm (4.3 inches)	86%	moderate
February Weather	5°C (41°F)	139 mm (5.5 inches)	84%	high
March Weather	10°C (51°F)	169 mm (6.6 inches)	84%	high
April Weather	14°C (58°F)	140 mm (5.5 inches)	80%	very high
May Weather	21°C (70°F)	151 mm (6.0 inches)	82%	extreme
June Weather	25°C (78°F)	112 mm (4.4 inches)	83%	extreme
July Weather	27°C (81°F)	101 mm (4.0 inches)	79%	very high
August Weather	25°C (78°F)	102 mm (4.0 inches)	76%	very high
September Weather	23°C (74°F)	85 mm (3.3 inches)	75%	very high
October Weather	16°C (62°F)	122 mm (4.8 inches)	74%	high
November Weather	8°C (47°F)	101 mm (4.0 inches)	85%	moderate
December Weather	6°C (43°F)	97 mm (3.8 inches)	88%	moderate