The Ravenel Bridge remains closed because of ice, authorities report.
Berlin G. Myers Bridge is also closed, according to S.C. Highway Patrol. All other bridges remain open.
An ice storm warning for the Lowcountry will remain in effect until 10 a.m. Thursday, according to the National Weather Service. Freezing rain will last through the morning, causing ice to accumulate up to a quarter of an inch.
Today's highs will be around 40 with lows around 30, the Weather Service reports. A near 100 percent chance of precipitation is expected with wind gusts up to 25 mph.
Crews have been treating the Ravenel Bridge with brine mix since 9:15 p.m. Tuesday and began treating it with granular salt around 3:45 a.m., according to state Department of Transportation spokesman Robert Kudelka.
CARTA buses will take the Don Holt Bridge for all Mount Pleasant routes due to the Ravenel Bridge closure, spokesman Daniel Brock said. Mount Pleasant's Towne Center will serve as a transfer point.
For more information on today's bus routes visit CARTA's website. Riders should expect delays.
The icy storm caused dangerous road conditions this morning. S.C. Highway Patrol received several reports of fallen trees and power lines throughout the area, Senior Trooper Hannah Wimberly said.
Highway Patrol urged drivers to stay off of the roads due to the hazards.
"The overpasses and shady areas are still dangerous and will continue to be. ...There aren't any specific roads to mention because they are all rough at this time," Wimberly said in an email.
Sheriff's deputies warned of similar dangers in Dorchester County.
"The driving conditions in Dorchester County are very poor at best, with down trees, power lines and a small accumulation ice on the highway. It is very dangerous to drive at this time," said Chief Deputy Sam Richardson.
Around 62,025 SCE&G customers reported power outages in South Carolina around 12 a.m. Wednesday. About 6,191 of those customers were in Charleston County, officials report. More than 21,557 were reported in Dorchester County.
The Highway Patrol reported dozens of accidents statewide as snow and ice-slicked highways knocked down trees and power lines and made driving hazardous. At 8 a.m., snow was reported in the Upstate with freezing rain farther south.
All interstates across South Carolina were passable, but there was snow and slush in some places.
Charleston International Airport remains open, but dozens of arriving and departing flights have been cancelled, mainly to and from cities affected by the winter storm.
"The runways are still open," said Airports Director Paul Campbell. "We just have issues at other airports with flights coming in."
Departures to and arrivals from New York, Chicago, Detroit, Charlotte, Atlanta, Houston, Washington, Baltimore, Dallas and Newark, N.J., were cancelled this morning. Not all flights to those destinations were affected, however.
Check departing flights here.
Check arrivals here.
As day broke, sleet began pinging off windows in Columbia and by rush hour, most of the streets were empty with only handful of cars crossing a bridge leading to the city's downtown and entertainment district. Streets nearby were covered with a mixture of snow and sleet, unvarnished by any vehicle tracks.
SCE&G brought in contract crews from utilities in Indiana, Ohio, Michigan and Kentucky to help its 1,200 workers restore power.
"Winter storms can be unpredictable. It's the combination of ice and wind that can lead to significant damage," said Keller Kissam, president of the company's retail operations.
Gov. Nikki Haley again declared a state of emergency as emergency officials worried that as much as an inch of ice accumulating on trees and power lines Wednesday into Thursday could knock out powers to thousands, especially in the Midlands.
At daybreak Wednesday, it was snowing from the Upstate in Anderson to the south Midlands near Walterboro. The Upstate and the mountains were expecting as much as 10 inches of snow. Snowfall totals were expected to be less moving southward toward the Midlands.
Freezing rain was reported along the coast. Winter storm warnings were posted for most of the state.
Authorities late Tuesday announced that Charleston County government offices, as well as city of North Charleston offices and public schools in Charleston County were to be closed Wednesday due to the wintry weather, along with Berkeley, Dorchester 2 and Dorchester 4 schools which had announced closings earlier in the day.
Ashley Hall School will be operating on a two-hour delay, a school spokeswoman said.
Here is a list of additional closings.
Conditions are expected to improve Thursday with partly sunny skies, highs in the upper 40s and lows in the mid 30s. A 50 percent chance of precipitation is expected with a trace of ice accumulation possible, the Weather Service reports.
Mostly sunny skies are expected Friday with highs in the upper 50s and lows around 40. A slight chance of rain is possible at night with winds up to 15 mph.
The Associated Press contributed to this report.