Charleston weather in September

In September, Charleston sees average daytime highs of 83°F and overnight lows near 71°F, with 5.1 in of rain across 13.3 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 85°F in the first days to 80°F by the end. The sky is clear or mostly clear about 37% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 42 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Charleston's 8th-clearest and 9th-windiest month. For the whole year in context, see Charleston's year-round climate.

Daytime high
83°
4th warmest
Overnight low
71°
9th coldest
Rainfall
5.1 in
13.3 wet days
Daylight
12 h 12 min
6:08 AM – 6:20 PM
Cloud cover
56%
8th clearest
Wind
8 mph
9th windiest
Solar energy
4.75 kWh/m²
Travel score
5.5
out of 10

Charleston is largest city in the U.S. state of South Carolina.

Density
470/km²
people per km²
Founded
1670

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 85°F in the first days to 80°F by the end.

A typical September day in Charleston reaches about 83°F in the afternoon and slips back to 71°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 77°F and 88°F. Set against its neighbours, September runs about 4°F cooler than August and about 7°F warmer than October.

50°60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18574
28574
38573
48573
58573
68573
78473
88472
98472
108472
118472
128472
138371
148371
158371
168371
178371
188370
198270
208270
218270
228269
238269
248169
258169
268168
278168
288068
298067
308067

How September really feels in Charleston

Once humidity and wind are folded in, September averages 7 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
7
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Charleston weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan59° / 43°3.28.410.14.8
Feb62° / 45°3.37.810.85.4
Mar67° / 51°3.28.211.86.6
Apr73° / 58°2.97.512.87.4
May80° / 66°2.7913.76.8
Jun85° / 73°5.116.314.14.5
Jul88° / 76°5.417.813.93.7
Aug87° / 75°6.318.913.23.9
Sep83° / 71°5.113.312.25.5
Oct76° / 61°4.07.811.27.4
Nov67° / 51°2.66.810.36.9
Dec62° / 46°3.47.79.95.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 19% of September, with mostly cloudy or overcast conditions the remaining 45%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15050
25149
35149
45248
55347
65545
75545
85644
95644
105743
115743
125842
135842
145842
155842
165743
175743
185743
195644
205545
215545
225545
235545
245545
255545
265446
275446
285446
295446
305446

Chance of precipitation in September

Any precipitation

Charleston gets around 5.1 in of rain over 13.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 44% and peaks near 52% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
152
251
350
450
549
648
747
847
946
1045
1145
1244
1344
1443
1543
1642
1742
1842
1942
2042
2142
2241
2341
2441
2540
2640
2739
2839
2938
3038

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the oppressive band about 47% of days. Sticky, muggy-or-worse air turns up on roughly 81% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1013175029
2014175028
3014185126
4015195025
5026205023
6026205022
7027215020
8028225019
9038225017
10039225016
110310225114
120411234913
130411234912
140412234911
150513234911
161513234810
17161323489
18161323488
19161423488
20271423487
21271423477
22381423466
23481423456
24491523445
25591523435
26691523425
277101623404
288101623394
298101724374
309111724364

Wind in September

Winds average 8 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
17light breeze
27light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 42 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 60 minutes over September. Sunrise moves from 5:58 AM to 6:18 AM, and sunset from 6:41 PM to 6:00 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:586:41
212.75:596:39
312.65:596:38
412.66:006:37
512.66:016:35
612.56:016:34
712.56:026:33
812.56:036:31
912.46:036:30
1012.46:046:28
1112.46:056:27
1212.36:056:26
1312.36:066:24
1412.36:076:23
1512.26:076:21
1612.26:086:20
1712.26:096:19
1812.16:096:17
1912.16:106:16
2012.16:116:14
2112.06:116:13
2212.06:126:12
2312.06:136:10
2411.96:136:09
2511.96:146:07
2611.96:156:06
2711.86:166:05
2811.86:166:03
2911.76:176:02
3011.76:186:00

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.75 kWh/m².

For context, solar energy here swings from a low near 2.62 kWh/m² to a high of 6.47 kWh/m² in May across the year — September's 4.75 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.0Bright
45.0Bright
55.0Bright
65.0Bright
75.0Bright
85.0Bright
94.9Bright
104.9Bright
114.9Bright
124.9Bright
134.8Bright
144.8Bright
154.8Bright
164.8Bright
174.7Bright
184.7Bright
194.7Bright
204.6Bright
214.6Bright
224.6Bright
234.5Bright
244.5Bright
254.5Bright
264.5Bright
274.4Bright
284.4Bright
294.4Bright
304.4Bright
Planning a trip in September

Hazard calendar for Charleston

In seasonPeak

In September, Charleston sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Charleston sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Charleston?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.5
Sightseeing
6th-best month of the year
6.4
Beach & pool
2nd-best month of the year

September is a reasonable time to visit Charleston for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Charleston in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Charleston sees daytime highs around 83°F and nights near 71°F. Pack light clothes. Worth having: rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

Sea temperature near Charleston in September

The nearest coast averages about 81°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 11 mi away) is warmest in August at about 83°F and coldest in February near 60°F.

It's comfortable for a long swim from Apr 25 to Nov 19 — about 6.9 months when the water holds above 68°F.

60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan61Cool
Feb60Cool
Mar61Cool
Apr66Cool
May73Refreshing
Jun80Warm
Jul83Tropical
Aug83Tropical
Sep81Warm
Oct75Warm
Nov68Refreshing
Dec64Cool

UV index in Charleston in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Charleston peaks around July 13 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJul 13UV 10Dec 19UV 3
UV index (midday)Level
Jan4Moderate
Feb5Moderate
Mar7High
Apr7Very high
May8Very high
Jun9Very high
Jul10Very high
Aug9Very high
Sep8Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Charleston in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Charleston is worst in March — around 20 µg/m³ PM2.5 (moderate), about 2.8× the cleanest month (December, 7 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodMar 1819 µg/m³Dec 177 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb12Good
Mar20Moderate
Apr14Moderate
May13Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep11Good
Oct8Good
Nov8Good
Dec7Good
Location & terrain

Where is Charleston?

Charleston sits at 32.8°N, 79.9°W, 20 ft above sea level, in United States. The nearest listed city is Mount Pleasant, 4.3 mi away.

Topography around Charleston

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Charleston.

Within 2 miles, the terrain around Charleston has only modest variations in elevation — a maximum elevation change of 79 ft around an average of 7 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 131 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 226 ft.

The land around Charleston is covered by water (51%) and artificial surfaces (23%) within 2 miles, water (34%) and trees (33%) within 10 miles, and trees (51%) and water (37%) within 50 miles.

2 miles
79 ft
10 miles
131 ft
50 miles
226 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Mount Pleasant 4.3 mi · North Charleston 6.2 mi · Hanahan 11 mi · Goose Creek 16 mi · Summerville 22 mi · Hilton Head 62 mi · Hilton Head Island 62 mi · Bluffton 66 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Charleston (32.7763°, -79.9327°, elevation 20 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).