Nate, which is now threatening Mexico's Yucatan peninsula as it becomes a Category 1 hurricane, killed at least 25 people in Central America, causing landslides and flooding and displacing hundreds of thousands of people.
Mexico has issued a yellow alert in eight municipalities of Quintana Roo ahead of the storm, which is expected to make landfall Saturday night.
The National Hurricane Center predicted it will continue to strengthen in the next 24 hours as it nears the Yucatan Peninsula as winds picked up to 137 kpm.
New Orleans Mayor Mitch Landrieu in Louisiana ordered the evacuation of some areas and imposed a mandatory curfew. The measure will come into effect from Saturday evening to Sunday morning as the eye of the storm is forecast to pass close to the city.
Alabama, Florida, Louisiana and Mississippi have declared a state of emergency.
Almost three-quarters of the U.S. Gulf of Mexico oil production is now offline as energy companies brace for the second major storm in as many months to hit the region.
Costa Rican President Luis Guillermo Solis has declared three days of national mourning and warned of further landslides following hours of heavy rains, where 600,000 people are without water. "We do not know yet what the size of the damage is, but it is a major crisis. There are isolated communities, bridges have fallen and roads have been cut, sewers have burst," he said at a press conference.
The government has closed schools and deployed thousands of police and rescue personnel to the worst affected areas as more than 7,000 people have been forced to leave their homes and are staying in shelters.
In total, 12 people died in Nicaragua, nine in Costa Rica, two in Honduras and two in El Salvador. 30 others are still missing.
On the Nicaraguan Pacific coast, the storm swept fishing and recreational boats, flooded shops and cut power lines.
"The losses are incalculable, we are economically affected and basic services have collapsed," said Mauricio Granja, an owner of a flooded restaurant in the tourist town of San Juan del Sur, about 130 kilometers south of the capital Managua.
More than 3,500 houses were damaged and 10,000 people were forced to leave their homes.