The October 2015 North American storm complex was an extratropical storm that triggered a high precipitation event, which caused historic flash flooding across North and South Carolina. The incipient cold front traversed the Eastern United States on September 29–30, producing heavy rain in multiple states. The system subsequently stalled just offshore. Tapping into moisture from the nearby Hurricane Joaquin, a developing surface low brought heavy, continuous rain to southeastern States, with the worst effects concentrated in South Carolina where catastrophic flooding occurred. The event culminated in South Carolina on October 4 when numerous rivers burst their banks, washing away roads, bridges, vehicles, and homes. Hundreds of people required rescue and the state’s emergency management department urged everyone in the state not to travel.^[4] Some areas of the state saw rainfall equivalent to a 1-in-1000-year event.

At least 25 deaths have been attributed to the weather complex: 19 in South Carolina, 2 in New York, 2 in North Carolina, 1 in Florida, and 1 in New Brunswick. Damage from the storm reached $2 billion.^[3]

South Carolina

Rainfall across parts of South Carolina reached 500-year event levels,^[13] with areas near Columbia experiencing a 1-in-1000 year event.^[14] Accumulations reached 24.23 in (615 mm) near Boone Hall by 11:00 a.m. EDT (15:00 UTC) on October 4.^[15] Charleston International Airport saw a record 24-hour rainfall of 11.5 in (290 mm) on October 3. Nearly 30,000 people were without power in the state.^[13] One woman drowned in Spartanburg on October 1 after her car was overwhelmed by flooding in an underpass.^[16] On October 2, a plane crashed along the South Carolina side of Lake Hartwell, killing all four occupants. The cause is currently unknown though there was light rain at the time of the incident.^[17] On October 3, the Charleston Historic District was brought to a virtual standstill with most roads closed because of flooding.^[18] Three deaths were confirmed in the state on October 2 and 3. Through the evening of October 3, highway patrol reported 500 traffic accidents and 104 flooded roads.^[19]