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September Weather in Charleston, United States

Last updated: June 24, 2025

In Charleston, United States, the average temperature in September is a pleasant 24°C (75°F). However, temperatures can vary significantly, dipping to a cool 10°C (49°F) and soaring to a scorching 37°C (99°F). During this time, expect around 94 mm (3.7 in) of precipitation spread over approximately 10 days, contributing to the region's average humidity of 76%.

September Temperature in Charleston

In September in Charleston, the average temperature is 24°C (75°F). Maximums can reach 37°C (99°F), while minimums can drop to as low as 10°C (49°F). This variability in temperatures makes Charleston a versatile destination for travelers seeking both warm and cooler climates.

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 24°C (75°F), with highs reaching up to 37°C (99°F) and lows dropping to around 10°C (49°F).
JanFebMarAprMayJunJulAugSepOctNovDec434854617076807874645046
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 94 mm (3.7 in) over a duration 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 94 mm (3.7 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec94165157149111991031269412475129
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 76%. With an average temperature of 24°C (75°F), this humidity feels like a warm, enveloping blanket that clings to your skin, making outdoor activities feel a bit sluggish and urging you to seek shade and hydration.

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 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%82%85%85%83%76%76%80%88%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.
JanFebMarAprMayJunJulAugSepOctNovDec46810111111109763
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 Weather6°C (43°F)94 mm (3.7 inches)86%moderate
February Weather9°C (48°F)165 mm (6.5 inches)86%high
March Weather12°C (54°F)157 mm (6.2 inches)86%very high
April Weather16°C (61°F)149 mm (5.9 inches)82%very high
May Weather21°C (71°F)111 mm (4.4 inches)85%extreme
June Weather24°C (76°F)99 mm (3.9 inches)85%extreme
July Weather27°C (80°F)103 mm (4.1 inches)83%extreme
August Weather26°C (78°F)126 mm (5.0 inches)76%very high
September Weather24°C (75°F)94 mm (3.7 inches)76%very high
October Weather18°C (65°F)124 mm (4.9 inches)80%high
November Weather10°C (51°F)75 mm (2.9 inches)88%high
December Weather8°C (47°F)129 mm (5.1 inches)88%moderate

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