Heavy rain, wind gusts and rising floodwaters from Hurricane Florence swamped the Carolinas early on Friday as the massive storm crawled toward the coast, threatening millions of people in its path with record rainfall and punishing surf.

Florence was downgraded to a Category 1 storm on the five-step Saffir-Simpson scale on Thursday evening and was moving west at only 6 mph.

The hurricane's sheer size means it could batter the U.S. East Coast with hurricane-force winds for nearly a full day, according to weather forecasters. Despite its unpredictable path, it was forecast to make landfall near Cape Fear, North Carolina, at midday on Friday.

North Carolina Governor Roy Cooper told a news conference that the "historic" hurricane would unleash rains and floods that would inundate almost the entire state in several feet of water.

National Weather Service forecaster Brandon Locklear said in a video briefing North Carolina would see the equivalent of up to eight months of rain in a two- to three-day period.

Early on Friday, the downtown area of the city of New Bern, on the Trent and Neuse rivers near the North Carolina coast, was underwater as emergency crews conducted several rescues, according to reports on social media.