Tropical Storm Nate gained force as it sped toward Mexico's Yucatan Peninsula Friday after drenching Central America in rain that was blamed for at least 21 deaths.
National Hurricane Centre said it was likely to reach the US Gulf Coast as a hurricane over the weekend, reports Ap.
Louisiana and Mississippi officials declared states of state of emergency ahead of its expected landfall Saturday night or early Sunday.
The storm had maximum sustained winds of 65 mph (100 kph) by Friday afternoon and was likely to strengthen over the northwestern Caribbean Sea on Friday.
The storm was located about 90 miles (145 kilometers) northeast of the Mexican resort island of Cozumel and had accelerated its north-northwest movement to 22 mph (35 kph).
The hurricane has sustained winds of 75 mph and is located 495 miles south of the mouth of the Mississippi River, in the southern Gulf of Mexico.
The US National Hurricane Centre warned that Nate could raise sea levels by 4 to 7 feet (1.2 to 2.1 meters) from Morgan City, Louisiana, to the Alabama-Florida border.
It had already had caused deadly flooding in much of Central America.
The centre added metropolitan New Orleans and Lake Pontchartrain to its latest hurricane warning.