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September Weather in Charleston, United States

Last updated: June 24, 2025

In Charleston, United States, the average temperature in September hovers around 25°C (76°F). However, be prepared for a range of temperatures: it can dip as low as 9°C (49°F) or soar up to 37°C (99°F). Rain is also on the radar, with a total precipitation of 59 mm (2.3 in) expected over 5 days. Humidity levels average at a comfortable 59%, making for a pleasant climate overall.

September Temperature in Charleston

In September in Charleston, the average temperature is 25°C (76°F). Maximum temperatures can reach 37°C (99°F), while minimums can drop as low as 9°C (49°F). Be prepared for a range of weather conditions when traveling to Charleston this month.

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 25°C (76°F), with highs reaching up to 37°C (99°F) and lows dropping to around 9°C (49°F).
JanFebMarAprMayJunJulAugSepOctNovDec414555607078828076635146
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 is 59 mm (2.3 in) over the course of 5 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 59 mm (2.3 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec8011613116119710987125591137690
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 59%. With an average temperature of 25°C (76°F), this humidity feels like a warm, enveloping blanket, making it quite pleasant for traveling as long as you stay hydrated and take periodic breaks in the shade.

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 59%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%79%77%78%82%81%75%61%59%69%82%88%
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.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109754
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 Weather5°C (41°F)80 mm (3.1 inches)82%moderate
February Weather7°C (45°F)116 mm (4.6 inches)79%high
March Weather13°C (55°F)131 mm (5.1 inches)77%very high
April Weather16°C (61°F)161 mm (6.3 inches)78%very high
May Weather21°C (70°F)197 mm (7.8 inches)82%extreme
June Weather26°C (78°F)109 mm (4.3 inches)81%extreme
July Weather28°C (82°F)87 mm (3.4 inches)75%extreme
August Weather27°C (80°F)125 mm (4.9 inches)61%very high
September Weather25°C (76°F)59 mm (2.3 inches)59%very high
October Weather17°C (64°F)113 mm (4.5 inches)69%high
November Weather10°C (51°F)76 mm (3.0 inches)82%moderate
December Weather8°C (47°F)90 mm (3.5 inches)87%moderate

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