While Hurricane Matthew was downgraded to Category 3 early Friday, The Weather Channel's Bonnie Schneider warned that the storm surge forecast has not changed.

"This is still a major hurricane and it's a very large one," she said. "Please don't let your guard down just because it's not a Category 4."

Schneider said storm surges of 4 to 6 feet were possible from West Palm Beach to Fort Pierce as well as along the Carolina coast. From 7 to 11 feet was predicted from Melbourne, Florida, to Savannah, Georgia.

In a 2 a.m. ET bulletin, the National Weather Service added: "Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. Large waves generated by Matthew will cause water rises to occur well in advance of and well away from the track of the center."