Hurricane Nate has made landfall in the US states of Louisiana and Mississippi as a category one storm, with wind gusts of nearly 140 kilometres per hour.
Nate, the fourth major storm to strike the United States in less than two months, killed at least 30 people in Central America before entering the warm waters of the Gulf of Mexico and bearing down on the US South.
The storm made landfall first in south-east Louisiana, then along Mississippi’s coast near the town of Biloxi.
The hurricane warning for New Orleans was downgraded to a tropical storm warning, and the mayor there lifted a curfew imposed earlier.
Forecasters said the hurricane would be downgraded back to a tropical storm by Sunday morning local time.
But a hurricane warning remained in effect for the Gulf Coast from Grand Isle Louisiana to the Alabama-Florida border, according to the US National Weather Service.
Evacuations were ordered along the central Gulf Coast and governors in Louisiana, Mississippi and Alabama have declared states of emergency.
“This is the worst hurricane that has impacted Mississippi since Hurricane Katrina,” Mississippi emergency management director Lee Smithson said.
“Everyone needs to understand that this is a significantly dangerous situation.”
About 5,000 people in southern Alabama were without power due to Nate, Alabama Power said.
Louisiana Governor John Bel Edwards urged residents to make final preparations quickly and stressed that Nate could deliver a storm surge reaching up to 3.3 metres in some coastal areas.
Ports closed, National Guard troops mobilised
Earlier, authorities made last-minute preparations as the hurricane intensified.
In Louisiana the National Guard mobilised 1,300 troops and positioned high-water vehicles, boats and even school buses from Baton Rouge to New Orleans to help with rescues.
Louisiana Governor John Bel Edwards said he spoke with President Donald Trump, who assured him the Federal Government was prepared to respond as well.
More than 40 per cent of manned oil- and gas-producing platforms in the Gulf of Mexico were evacuated, according to the Interior Department.
Some airports in southern US states were closed, as were major shipping ports across the central US Gulf Coast.
The US Coast Guard ordered a halt to all traffic beginning at 8:00am local time for several ports in New Orleans, Mississippi, Alabama and Florida.
New Orleans, which sits near the mouth of the Mississippi River, is an important transit point for energy, metals and agricultural commodities moving to overseas and domestic markets.
Gary LaGrange, executive director of trade group Ports Association of Louisiana, said he expected traffic restrictions to be lifted quickly once the fast-moving storm passed.
“It’ll be short-lived, based on the projected path and movement of the storm, unless an unlikely event happens such as two vessels colliding,” he said.
Vessels were still moving to secure berths at the ports on Saturday morning, he said.