September starts out hot and humid, however, mornings become more comfortable as the month progresses. About 24 days will be humid, most likely early in the month.
Daytime high temperatures tend to around 84-86 F (29-30 C) early in the month, cooling to about 80-81 F (27 C) near the end of the month.
On average, about 3-5 days this month record highs at or above 90 F (32 C), mostly early in the month.
The record high temperature in Charleston during September is 99 F (37.2 C).
Late night and early morning lows will tend to be near 73-75 F (23-24 C) early in the month, cooling to about 68-70 F (20-21 C) near the end of the month.
A few of the cooler mornings, especially later in the month, can dip down to near 57 F (14 C).
The record low temperature in Charleston during September is 42 F (5.6 C).
How Much Rain in April?
On average, you can expect 7 sunny, 10 partly sunny, and 13 mostly cloudy days this month.
Some measurable rain falls on 8-9 days this month, however, only about 3 days record significant rainfall of 0.5 inches (12.7 mm).
About 5 days this month (mostly early in the month) will record thunderstorms.
The number of daylight hours decreases rapidly this month from about 12.8 hours on the 1st to 11.9 hours by the 30th.
The prevailing wind speeds during this month are light to gentle at 4-12 mph (6-19 kph) but briefly can be moderate at 13-18 mph (20-28 kph) with stronger gusts possible in thunderstorms.
September is a great time for the beach as the ocean temperature remains warm, averaging around 82 F (28 C) early in the month, and cooling to 79 F (26 C) near the end of the month.
The risk of a tropical storm or hurricane activity peaks in September, with a named tropical storm or hurricane passing within 175 miles of Charleston about every two years.
What to Wear in Charleston During September?
This month starts out very warm and humid and summer attire works well so pack light and airy clothes, shorts, an umbrella, or a waterproof jacket for the rainy days plus sunscreen for the beach.
Some cooler weather is likely towards the end of the month so also pack a lightweight jacket and long pants for the cooler mornings.
Don’t forget some nice evening shoes and a good pair of walking shoes.
Things to Do in Charleston in September
Although the weather will be getting cooler this month, there should still be more than enough warm and sunny days to consider taking a pay-what-you-wish Charleston walking tour.
The Charleston Riverdogs will be ending their season in September, so you might want to go and catch one of their last games of the year.
The Lowcountry Jazz Festival is also usually scheduled during the month of September, so if you're looking for a concert or live musical performance to attend, you might want to consider attending one of their shows.
For even more great ideas, make sure to read our full post covering things to do in Charleston in September.