The rare late-season hurricane named Ida is moving across the Gulf of Mexico and bearing down upon several Gulf Coast states, prompting hurricane warnings and evacuations.
The U.S. National Hurricane Center has issued a hurricane warnings for southeastern Louisiana that stretches to the Florida Panhandle. It does not include the city of New Orleans, the hurricane center said.
Heavy rains are expected to be the worst of the hurricane.
Ida has weakened from a Category 2 to a Category 1 storm, with maximum expected sustained winds expected of 95 mph.
Coastal residents in Grand Isle, La., are already packing up their belongings, and Gov. Bobby Jindal has declared a state of emergency.
"People are already heading out," said Grand Isle resident Neal Perrillioux. "They aren't taking any chances."
Stretches of southeast Louisiana outside of levee protection are the main concern. Forecasters say those areas could experience flooding.
Parts of northern Florida have cancelled school, and lowland evacuations are being encouraged. Winds are stirring as far south as Miami.
In the Gulf itself, oil companies are on high alert, evacuating workers and halting production on some platforms.
November hurricanes are rare. The last one to make landfall in the U.S. this late in the season was Hurricane Kate in 1985.
El Niño Played Role in Season's Storms
Ida is only the third hurricane of this season in the Atlantic Ocean. Experts say that El Niño likely played a part in keeping the season mild.
"El Niño generally produces stronger wind shear in the Atlantic. That's when the winds are different in the upper and lower levels of the atmosphere, tends to tear hurricanes apart and we saw that with a number of systems this year," said James Franklin, hurricane specialist unit chief with the National Hurricane Center.
Ida's current has already pulled days of heavy rains into El Salvador, where at least 124 people have died.
Hurricane Ida swept through the Nicaragua's Atlantic Coast Thursday, leaving nearly 500 homes, as well as roads, bridges and public buildings destroyed.
ABC News' Monica Nista and The Associated Press contributed to this report.