Intermittent downpours and gusts strong enough to knock over trees were expected through the Charleston area on Saturday morning.
The rain and wind were worse in counties to the north.
Folly Beach planned to reopen to non-residents at 1 p.m., said Mayor Tim Goodwin.
At 11 a.m. tropical storm and flash flood warnings were dropped for Charleston and the tri-county area. The National Hurricane Center sensors reported Florence was barely a tropical storm, spinning out 45 mph winds at its core about 40 miles south of Florence, the city.
No tropical storm force winds — 39 mph or more — were being reported in the state, according to S.C. Climate Office severe weather liaison Mark Malsick earlier.
The storm inched to the west at only 2 mph, spilling downpours as it went.
At the National Weather Service office at Charleston International Airport, the highest recorded gust was 53 mph, Friday evening.
We are continuing to urge people not to be out there just driving around. Rain continues to fall and saturate the ground. We’ve responded to over 100 trees down overnight. Working with SCDOT to clear roadways as we get the calls. #Florence 🌀🚔👷♂️@SCEMD— Trooper Bob (@TrooperBob_SCHP) September 15, 2018
At Lake Moultrie in Berkeley County, closer to the heart of the storm, the highest gust was 47 mph. Some trees and power lines had been reported down, particularly in Berkeley County.
A Weather Service meteorologist in Charleston said the National Hurricane Center could well downgrade Florence to a tropical depression, a weaker storm, on Saturday afternoon or evening.
"It certainly started decaying. It's transitioning to a heavy rain event," said Weather Service meteorologist Steven Taylor.
National Hurricane Center specialist Stacy Stewart said the rain was producing catastrophic flooding over both South and North Carolina.
The storm was still expected to crawl across the state past Columbia, then turn north into mountains on Sunday.
Downed trees may become more common later today. The combination of moderate rain, saturated ground, and gusty winds will result in health and unhealthy trees to uproot. https://t.co/AbW8NOtfmy— NWS Charleston, SC (@NWSCharlestonSC) September 15, 2018
Disastrously flooding rain continued to be considered the main threat to the state — three years after an historic flood and two years after floods from Hurricane Matthew's rain devastated towns such as Nichols along the North Carolina border.
As much as 30 inches of rain could fall in spots near the eye of the storm. But only 4 inches were expected in the northern reaches of the tri-county and less than an inch in Charleston. A storm surge of anywhere from 2 to 6 feet was expected along the South Carolina coast from Charleston north.
"The rain from Florence may go well past one or more all-time state records for rainfall from a hurricane or tropical storm," said meteorologist Bob Henson with the private company Weather Underground.
"North Carolina’s state rainfall record from a hurricane is 24.06 inches from Hurricane Floyd in 1999. South Carolina’s is 17.45 inches from Hurricane Beryl in 1994," he said.
Florence's storm surge reached 10 feet at some North Carolina gauges, breaking long-standing records at those locations, said meteorologist Jeff Masters, with Weather Underground.
"Hurricane Florence was only a Category 1 storm on the Saffir-Simpson wind scale when it struck, but the hurricane’s massive wind field brought a huge storm surge to the coast that broke all-time high-water records as much as 65 years old," Masters said.