Ian roared ashore as a Category 1 storm near Georgetown with sustained winds of 85 miles per hour (140 kilometres per hour) at 2.05pm (eastern time) on Friday. The small town is around 60 miles north of the city of Charleston.
The storm accelerated as it moved towards the coast and was traveling north at 15mph (24 km/h), a National Weather Service spokesman said on Friday afternoon.
A hurricane warning was in effect from the Savannah River outside of Savannah, Georgia up to Cape Fear, North Carolina.
A storm surge warning was issued for the Savannah River up to Cape Fear along with the Neuse River, North Carolina and St Johns River, Florida.
The NHC warned that at high tidde, peak storm surge could be 4-7ft along a 130-mile stretch from Isle of the Palms, north of Charleston, to Little River Inlet, north of Myrtle Beach.
Ian is forecast to turn northwest tonight and will move inland across eastern South Carolina and central North Carolina into Saturday, according to the NHC.
The system should weaken rapidly after landfall and become a post-tropical cyclone overnight before dissipating over western North Carolina or Virginia late on Saturday.
More than 300,000 people were without power in North Carolina and South Carolina on Friday, according to tracker poweroutage.us.
On Friday morning, heavy rain from Ian deluged the cities of Charlotte and Greensboro in North Carolina, and Virginia Beach, Virginia.
A state of emergency and warnings for coastal areas were issued for Georgia, the Carolinas, and Virginia.
Ian is one of the most powerful hurricanes to ever hit the US with the death toll and magnitude of destruction only beginning to emerge. More than 2.5 million Floridians have also been left without power and thousands are stranded.
Ian made landfall in western Cuba early this week with authorities in the Pinar del Rio province evacuating 50,000 people from the area. The entire island was left in blackout after the power grid failed.