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September Weather in Charleston, United States

Last updated: June 24, 2025

In September, the average temperature in Charleston, United States hovers around 21°C (71°F), with a minimum of 8°C (47°F) and a sweltering maximum of 34°C (93°F). Expect 91 mm (3.6 in) of precipitation over approximately 10 days, contributing to an average humidity of 68%. Whether you’re soaking up the sun or dodging the occasional shower, prepare for a diverse climate!

September Temperature in Charleston

In September in Charleston, the average temperature is 21°C (71°F). Maximum temperatures can reach 34°C (93°F), while minimum temperatures can dip as low as 8°C (47°F). Overall, it's advisable to pack for both warm days and cooler evenings while traveling during this time.

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 34°C (93°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec343743536372787670614639
Data source: Temperature data for Charleston 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 Charleston

In Charleston in September, the precipitation amount totals 91 mm (3.6 in) over a span of 10 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 91 mm (3.6 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec66107103111118941441269113082102
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Charleston

In Charleston in September, humidity is 68%. With an average temperature of 21°C (71°F), this humidity feels like a warm embrace, making traveling a bit sticky but also inviting for leisurely strolls and outdoor adventures.

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 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%81%78%70%69%62%65%68%74%82%80%
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.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
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.
 TemperaturePrecipitationHumidityUV
January Weather1°C (35°F)66 mm (2.6 inches)84%moderate
February Weather3°C (37°F)107 mm (4.2 inches)82%moderate
March Weather6°C (43°F)103 mm (4.0 inches)81%high
April Weather12°C (53°F)111 mm (4.4 inches)78%very high
May Weather17°C (63°F)118 mm (4.6 inches)69%very high
June Weather22°C (73°F)94 mm (3.7 inches)69%very high
July Weather26°C (79°F)144 mm (5.6 inches)62%very high
August Weather25°C (77°F)126 mm (5.0 inches)65%very high
September Weather21°C (71°F)91 mm (3.6 inches)68%very high
October Weather16°C (61°F)130 mm (5.1 inches)74%high
November Weather8°C (47°F)82 mm (3.2 inches)82%moderate
December Weather4°C (39°F)102 mm (4.0 inches)80%low

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