The rain that has wreaked havoc on the region this week is on track to end, but commuters in parts of the Bay Area are poised to be challenged by a new weather hazard — black ice, forecasters said.

Black ice could coat roadways in Santa Rosa, Mill Valley, San Rafael, Kentfield and in parts of the East Bay around Concord and Livermore on Friday morning as temperatures plunge, said Steve Anderson, a forecaster with the National Weather Service in Monterey.