Washington DC - Hurricane Erin weakened to Category 2 on Tuesday but continues to threaten part of the East Coast with life-threatening flooding, forecasters said.

The storm, which underwent historically rapid intensification and briefly peaked at Category 5 on the Saffir-Simpson scale, swamped homes and roads in the US island territory of Puerto Rico.

Although its core is projected to remain far offshore, meteorologists remain concerned by Erin's large size, with tropical-storm-force winds extending hundreds of miles from its core.

Environment and Climate Hurricane Erin downgraded to Category 3 as it lashes the Caribbean with rain

Environment and Climate Hurricane Erin threatens East Coast after drenching the Caribbean

In an afternoon update, the US National Hurricane Center said Tropical Storm Warnings were no longer in place for the Bahamas and Turks & Caicos Islands, but remain in place for parts of North Carolina.

Erin was several hundred miles southeast of North Carolina and winding its way north-northwest.

"This means there's the danger of life-threatening inundation of two to four feet of inundation above ground level," NHC director Michael Brennan said.

He added there was "potential for destructive wave action on top of that storm surge, that could result in severe beach and coastal damage," making coastal roads impassable.

A broader swath of coastline, from North Carolina to southern Virginia, is under a lower-grade Tropical Storm Watch.

US media reported dozens of people have had to be rescued from dangerous rip currents, surges of water that run against the tide.