Charleston weather by month
Charleston runs from about 11°C in January to 28°C in July, with August the wettest month at 218 mm.
warmest month
July
28°C
coolest month
January
11°C
wettest month
August
218 mm
worst air month
July
11 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 11°C | 110 mm | 243 h | 10 |
| February | 12°C | 109 mm | 242 h | 9 |
| March | 16°C | 136 mm | 269 h | 9 |
| April | 19°C | 91 mm | 340 h | 9 |
| May | 23°C | 101 mm | 342 h | 10 |
| June | 27°C | 105 mm | 380 h | 9 |
| July | 28°C | 164 mm | 346 h | 11 |
| August | 26°C | 218 mm | 318 h | 9 |
| September | 25°C | 133 mm | 268 h | 9 |
| October | 20°C | 12 mm | 307 h | 6 |
| November | 17°C | 61 mm | 249 h | 7 |
| December | 11°C | 79 mm | 215 h | 11 |
About 3,519 hours of sun a year. Roughly 132 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.