"We declared a state of emergency…that allowed me to activate 1,800 National Guardsmen to help," Haley told reporters on Tuesday.
She stated that in addition to medical evacuations ahead of the storm, the state would begin coastal evacuations of residents on Wednesday.
On Monday in Florida, Governor Rick Scott announced a state of emergency for every county in his state because Hurricane Matthew could bring significant damage and pose a threat to people's lives.
According to the US National Hurricane Center, Matthew is expected to reach South Carolina on Friday or Saturday.
The hurricane, which made landfall in Haiti, on Tuesday morning, is the first Category 4 storm to hit that country since Cleo in 1964, according to the NHC. Category 4 hurricanes have sustained winds of between 130 and 156 miles per hour (209-251 kilometers per hour).