"While the storm is still on, don't go outside", Scott said.
Major southern Florida population centers like Miami and West Palm Beach appeared to have avoided the worst of the storm. Forecasters say more than 15 inches of rain could still cause a 9ft storm surge in the state.
Special concern surrounded Jacksonville's St. Johns River, which could be overwhelmed by water pushed into it by the storm.
Matthew, the fiercest cyclone to affect the United States since Superstorm Sandy four years ago, triggered mass evacuations along the coast from Florida through Georgia and into SC and North Carolina. She also said that while shelters remain open, residents shouldn't try to travel far; most counties along the S.C. coast are already under curfews. First responders unable to reach her after she suffered a heart attack. At least 13 people on the Caribbean island have also died from outbreaks of cholera since the storm, and around 61,500 people were in shelters, officials said.
After battering Florida's east coast, a weakened Hurricane Matthew churned slowly north early Saturday, bringing risky storm surges and powerful winds to Georgia and SC.
Across Florida, Georgia, North and SC and Virginia power has mostly been restored after 1.6 million people were hit by blackouts in the wake of the storm.
Matthew is expected to arrive near or over the shores of SC by Saturday and over to North Carolina by Saturday evening.
Winds were already blustery in Hilton Head, South Carolina, with one gust measured at 63 miles per hour.
Up until then, the centre, or eye, stayed just far enough out at sea for coastal communities not to feel the full force of Matthew's winds. It was moving north at 12 miles-per-hour.
The storm was blamed for at least 11 deaths in the United States-five in Florida, three in North Carolina and three in Georgia.
Even though Matthew made its first technical U.S. landfall Saturday morning, part of the storm's eyewall - the hurricane's strongest section - passed over parts of coastal Florida, Georgia and SC from Friday into Saturday, helping to flood low-lying areas, down trees and make some roads impassable. Deal has activated 1,000 National Guard troops. Flash flood warnings were issued in several locations across the states, including near the state line and the Summerville area near Charleston. Officials in some areas are going door to door, urging people to leave. Signs were blown over, and power was out across the island.
Hurricane Matthew is gone, but the disaster it unleashed will slowly unfold this week as rivers across eastern North Carolina rise to levels unseen since a similar deluge flooded thousands of homes and businesses during Hurricane Floyd in 1999.
Charleston had its third-highest tide crest in history and the highest since Hurricane Hugo in 1989, the weather service said.