(NewsNation) — A hurricane warning was issued Thursday for the entire coast of South Carolina as Ian once again regained strength, reaching hurricane-force winds while turning northward.

Though downgraded briefly to a tropical storm Thursday morning, the National Hurricane Center warned Ian is expected to again make landfall near Charleston as a Category 1 hurricane.

The National Hurricane Center says the storm’s maximum sustained winds increased Thursday to 75 mph. It was centered about 240 miles south of Charleston and moving northeast at 10 mph.

According to NHC forecasters, landfall will likely take place between 8 and 11 a.m. Friday.

“If you haven’t yet made plans for every contingency, this afternoon is the time to do so,” said Gov. Henry McMaster at a Thursday media briefing. “We can expect to experience a lot of rain throughout the state along with dangerous storm surge in low-lying coastal areas. With the potential for hurricane-force winds along our coast, it’s important for South Carolinians to plan now.

Forecasters say people can expect several feet of ocean water could surge into low areas along the coast, and flooding could rival or even slightly exceed recent hurricanes.

Charleston Mayor John Tecklenburg cautioned residents to “take this storm seriously.”

“Tomorrow, stay home and stay out of harm’s way,” Tecklenburg said.

Up to a foot of rain is forecast for parts of Northeast Florida, coastal Georgia and the Lowcountry of South Carolina in the coming days, according to Robbie Berg, senior hurricane specialist with the National Hurricane Center. As much as 6 inches could fall in southern Virginia as the storm moves inland over the Carolinas, and the center said landslides were possible in the southern Appalachian mountains.

Local agencies are opening emergency shelters based on need and storm conditions, according to the governor’s office. Shelter locations, when open, will be posted on the South Carolina Emergency Management Division’s website and mobile app.

Ian struck Florida as a monstrous Category 4 storm, with 150 mph winds that tied it for the fifth-strongest hurricane ever to hit the U.S.

Ian flooded homes on both the state’s coasts, cut off the only bridge to a barrier island, destroyed a historic waterfront pier and knocked out electricity to 2.67 million Florida homes and businesses — nearly a quarter of the state’s utility customers.

As authorities throughout southwest Florida assessed the damage, the death toll began to mount.

Sheriffs in southwest Florida said 911 centers were inundated by thousands of stranded callers, some with life-threatening emergencies. 

The Associated Press contributed to this report.