S.C. Code of Laws Title 59 Education, Chapter 1 SECTION 59 1 425,

school calendars must:
-Cover at least nine calendar months
-Not start before the third Monday in August
-Use 180 days for instruction
-Use three days for collegial professional development
-Use no more than two days for preparation of opening of schools (teacher work days)
-Use the remaining five days for teacher planning, academic plans, and parent conferences
-In addition, schools must have three weather makeup days built into their academic calendars. If there is severe weather

and the district is forced to close school one day, the school must use one of its three built-in makeup days to make that day up.
-If bad weather causes us to cancel school for more than three days, once we use all three makeup days, the board can vote (with a majority vote) to forgive up to three additional days.