The state-by-state death toll so far is: North Carolina, 7 deaths; Georgia, 4 deaths; and Florida, 6 deaths. North Carolina is bracing itself for up to a meter of sustained rainfall.
Matthew has left 2.2 million households and businesses without power across the Southeast region.
The three states are witnessing major power outages. An ongoing cholera outbreak has already killed roughly 10,000 people and sickened more than 800,000 since 2010, when the infectious disease was introduced into the country's biggest river from a United Nations base where Nepalese peacekeepers were deployed. The National Weather Service measured a record tide level of more than 12 feet at the mouth of the Savannah River, which borders both South and North Carolina. Forecasters warned that the combination of a unsafe storm surge, the tide and large waves could cause rising waters to move inland from the shoreline to flood normally dry areas near the coast.
Those states, as well as North Carolina, declared states of emergency, empowering their governors to mobilize the National Guard.
On Saturday, Charleston County Emergency Medical Services in SC suspended its service countywide, warning that high-span or exposed bridges are unsafe for public travel due to high winds.
Almost 17 inches of rain were recorded at Hunter U.S. Army Airfield in Savannah, Georgia over a 48-hour period, according to the National Hurricane Center.
The AP notes that according to forecasters, rain and storm surge may be more unsafe than the eye-popping wind speeds at the center of the storm: "They said the major threat to the Southeast would not be the winds - which newer buildings can withstand - but the massive surge of seawater that could wash over coastal communities". The storm had cut power to some 827,000 households in Florida, he said.
The official death toll remains at 336, but the government says this tally only includes fatalities confirmed by visits to villages. The city's beaches will reopen Saturday at noon as officials continue to assess the damages.
"We will be using funds from existing operations to help clear debris, fix bridges and roads, help kids return to school, and clean up mudslides, which require heavy and expensive equipment", Kim said.
The governor said its too soon to know just how much damage Matthew has caused. "Many of you will remember Hurricane Sandy, where initially people thought this doesn't look as bad as we thought, and then suddenly you get massive storm surge and a lot of people were severely affected".
Two million people were told to move inland to escape a potentially catastrophic blow from a storm that left more than 280 dead in its wake across the Caribbean, but many hunkered down and hoped for the best.
The hurricane center also stressed that there is a risk of "life-threatening inundation" during the next 36 hours along the Florida east coast, the Georgia coast, and the SC coast from Jupiter Inlet in Florida to the South Santee River in SC.
Mayor Nancy Shaver said up to half the population in vulnerable zones had refused to evacuate. Meanwhile, all toll suspensions remained in effect and will remain suspended until at least Sunday night.