Hurricane Erin is set to threaten large stretches of the US East Coast on Wednesday, bringing storm surges, rip currents, and coastal flooding, forecasters have warned.
The Category 2 storm, currently over the Atlantic Ocean, is not expected to make landfall in the US but authorities have cautioned that high waves, flooding and road closures are likely.
North Carolina is expected to be one of the worst hit areas, but no-swimming advisories have been issued at beaches as far north as New Jersey and Delaware.
Erin has already barrelled through the Caribbean, drenching Puerto Rico, and is packing maximum sustained winds of 105mph (168km/h), said the US National Hurricane Center (NHC).
The Outer Banks, a string of barrier islands off North Carolina, are already bracing for heavy surf and high winds.
Speaking at a news conference on Wednesday, North Carolina Governor Josh Stein warned people to begin preparing for the storm, which he said would bring life threatening currents.
“It’s a serious storm,” he said. “No one should be in the ocean.”
Stein said the state had three “swift-water rescue teams” and 200 National Guard troops ready to assist people with boats, aircrafts and other vehicles.
Authorities have ordered mandatory evacuations of Hatteras and Ocracoke amid fears that the main highway linking them to other islands could become impassable.
Stein urged people to take the orders seriously, telling them to “take action now before it’s too late”.
Meteorologists warn the hurricane is unusually big, with tropical storm winds spanning 230 miles from its core, and is forecast to get even bigger.

On Wednesday and Thursday, the NHC said Erin would move between Bermuda and the US East Coast.
Officials warned that life-threatening inundation from coastal flooding was possible from Wednesday, with waves up to 15ft (4.6m). Some roadways could be under water for several days.
At least 60 people were rescued on Monday from rip currents – which flow away from the shore and can quickly pull people into the ocean – at Wrightsville Beach, North Carolina.