McMaster is expected to sign the evacuation order Friday, but he shared his plans Thursday to get people ready as soon as possible to the leave vulnerable coastal areas.
The evacuation order for areas east of Interstate 95 and some areas to its west takes effect Saturday at 8 a.m., Deal said in a statement.
Gov. Henry McMaster said he plans on issuing mandatory coastal evacuations starting at 10 a.m. Saturday along with a complete lane reversal of Interstate 26 from Charleston to Columbia as Hurricane Irma heads toward SC.
US president Donald Trump has approved the Palmetto State's emergency declaration, issuing an order on Thursday afternon confirming that "an emergency exists in the State of SC".
See map of evacuated areas here or below. As of 10 a.m. CDT Thursday, the eye of Hurricane Irma was located about 120 miles southeast of Grand Turk Island and was moving west-northwest at 16 mph with winds of 175 mph.
The National Hurricane Center also put Georgia and the Carolinas on alert as concerns mount that the storm could head up the east coast.
South Carolina Gov. Henry McMaster, also declared a state of emergency. On Thursday afternoon, Deal added 24 more counties to that list.
State emergency officials said they don't want people to panic but want those in hurricane-prone areas to be prepared.
"You need to start preparing for some type of impact", Cooper said.
Students at coastal colleges in Georgia have begun evacuating ahead of a potential Irma landfall.
Georgia issued mandatory evacuation orders for coastal areas, including Savannah, starting Saturday, while portions of the southern tip of Florida are already under mandatory or voluntary evacuation orders.
The school will remain closed until Tuesday. Admission to the game is free.