Downtown Charleston may experience flooding in addition to unusually cold temperatures Wednesday morning. File/Andrew J. Whitaker/Staff

A sudden cold front is hitting harder than expected this morning, and forecasters are advising that people bundle up and expect a few hazardous road conditions.

All lanes were closed on westbound Interstate 20 near Columbia between Augusta Road and South Lake Drive for more than an hour due to black ice on the highway, which caused six crashes, Highway Patrol said. The highway reopened shortly after 8 a.m., they said.

Charleston is experiencing lower temperatures than previously predicted due to winds of 15 to 20 mph, according to the National Weather Service. It's an unusual level of cold for mid-November, the Service said.

Forecasters suggested that children waiting for school buses should be especially prepared for the cold, dressed for temperatures in the upper 20s to lower 30s.

The Service also issued a coastal flood advisory until 11 a.m., saying some roads in downtown Charleston will become impassable. As of 8:15 a.m., no road closures had been announced.

No black ice has been reported in Charleston.

This story will be updated as closures occur.

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Reach Fleming Smith at 843-937-5591. Follow her on Twitter at @MFlemingSmith.

Fleming Smith covers breaking news for the Charleston area. A native Georgian, she previously covered breaking news and features for The Wall Street Journal and The Atlanta Journal-Constitution.