Charleston, South Carolina, is a city defined by its humid subtropical climate, which makes snowfall an extremely rare event. While the sight of snowflakes is possible during the coldest months, accumulation that sticks to the ground is highly unusual. The city’s low latitude and proximity to the Atlantic Ocean contribute to very mild winters where temperatures rarely sustain conditions for snow.
Historical Frequency and Accumulation
Measurable snowfall in Charleston is an infrequent event, typically occurring only once every few years. The area often sees trace amounts of snow or flurries, which melt on contact due to warm ground temperatures. Records show that the Lowcountry averages a snowfall event significant enough to measure only about once every three years. The most substantial snow event on record occurred on December 23, 1989, when the city received 6.0 inches of snow in a single day. Another notable event was the January 3, 2018, storm, which blanketed the area with 5.3 inches, representing the third-largest snowfall in the city’s recorded history. The snowiest calendar year was 1989, which saw a cumulative total of 8.9 inches.
Climatic Factors Limiting Snowfall
Charleston’s location on the coast at a relatively low latitude is the primary factor limiting the frequency of snow events. The city’s humid subtropical climate results in average winter daytime highs often near 60 degrees Fahrenheit and overnight lows around 40 degrees Fahrenheit. These mild temperatures prevent the atmospheric column from staying consistently below the 32-degree Fahrenheit threshold required for snow formation and survival to the ground. A significant warming influence comes from the nearby Atlantic Ocean and the Gulf Stream, which helps moderate temperatures throughout the winter. For snow to occur, a specific and rare meteorological alignment must take place: a deep, strong push of cold air from the continent must perfectly coincide with a coastal mid-latitude cyclone that provides moisture.
Local Impact of Rare Snow Events
Because snowfall is so uncommon, the local impact of even a small accumulation is often disproportionately large. The city’s infrastructure is not prepared for winter precipitation, leading to immediate widespread school closures and significant travel disruptions. Bridges, such as the Arthur Ravenel Jr. Bridge, are particularly susceptible to closure due to icing, as the city has limited de-icing capabilities compared to northern regions. When snow does fall, it is generally met with excitement and treated as a novelty by residents. However, the snow typically melts within a couple of days, as the mild climate quickly reasserts itself, often pushing temperatures back into the 60s Fahrenheit.