South Carolina has a humid subtropical climate (Köppen climate classification Cfa), although high-elevation areas in the Upstate area have fewer subtropical characteristics than areas on the Atlantic coastline. In the summer, South Carolina is hot and humid, with daytime temperatures averaging between 86–93 °F (30–34 °C) in most of the state and overnight lows averaging 70–75 °F (21–24 °C) on the coast and from 66–73 °F (19–23 °C) inland. Winter temperatures are much less uniform in South Carolina.
Coastal areas of the state have very mild winters, with high temperatures approaching an average of 60 °F (16 °C) and overnight lows around 40 °F (5–8 °C). Inland, the average January overnight low is around 32 °F (0 °C) in Columbia and temperatures well below freezing in the Upstate. While precipitation is abundant the entire year in almost the entire state, the coast tends to have a slightly wetter summer, while inland, the spring and autumn transitions tend to be the wettest periods and winter the driest season, with November being the driest month. The highest recorded temperature is 113 °F (45 °C) in Johnston and Columbia on June 29, 2012, and the lowest recorded temperature is −19 °F (−28 °C) at Caesars Head on January 21, 1985.
Snowfall in South Carolina is somewhat uncommon in most of the state, while coastal areas receive less than an inch (2.5 cm) annually on average. It is not uncommon for the state (especially the southern coast) to receive no recordable snowfall in a given year. The interior receives a little more snow, although nowhere in the state averages more than 12 inches (30 cm) of snow annually. The mountains of extreme northwestern South Carolina tend to have the most substantial snow accumulation. Freezing rain and ice tend to be more common than snow in many areas of the state. Road bridges in South Carolina are commonly marked, "Bridge ices before road".
South Carolina is also prone to tropical cyclones and tornadoes. Two of the strongest hurricanes to strike South Carolina in recent history were Hurricane Hazel (1954) and Hurricane Hugo (1989).