Hurricane Ida was upgraded to Category 2 on Saturday as it intensified on its way toward the U.S. Gulf Coast, where people were preparing for it to make landfall as a life-threatening Category 4 storm in what officials said could be the strongest hurricane to hit Louisiana in at least 165 years.
Ida, which was expected to make landfall on Sunday, the 16th anniversary of Hurricane Katrina, had moved away from Cuba and was moving toward the Louisiana coast with sustained wind speeds of 105 miles per hour, the National Hurricane Center said in an advisory.
Gov. John Bel Edwards of Louisiana said that Ida would be the strongest storm to hit the state since at least the 1850s. In 1856, a hurricane leveled Louisiana’s Last Island and killed more than 200 people, according to the National Weather Service.
Mr. Edwards warned evacuees in a news briefing on Saturday, a day after he declared a state of emergency, that their “window of time is closing.”
“It is rapidly closing,” he said.
The state authorities are preparing to respond and have almost 200 buses standing by to evacuate Louisianans, including nursing home residents, he said. The authorities have closed more than 200 floodgates, and more than 5,000 National Guard members, along with rescuers from the Federal Emergency Management Agency, are preparing to help in relief efforts.
“Ida is expected to be an extremely dangerous major hurricane when it approaches the northern Gulf Coast on Sunday,” the hurricane center said on Saturday, adding that parts of Louisiana could expect life-threatening floods when the storm makes landfall.
The center of the storm would most likely reach Louisiana early on Monday as a hurricane, with maximum winds of 110 m.p.h. and gusts of up to 130 m.p.h., according to the center’s tracking model and the National Weather Service in Shreveport, La. Ida was expected to then turn northward and weaken as it churned through Louisiana and western Mississippi, forecasters said.
By 2:30 p.m. Saturday, the Weather Service in Shreveport reported that Ida had become a Category 2 hurricane.
Tropical storm-force winds could arrive as early as Saturday night, the National Weather Service in New Orleans said on Twitter. The Weather Service urged those under evacuation orders to leave. “Some areas may be uninhabitable for weeks,” it said on Twitter.
Sections of the Louisiana and Mississippi coasts should be prepared for life-threatening storm surges of up to 15 feet on Sunday, the center said.
Mayor LaToya Cantrell of New Orleans ordered all residents outside the city’s levee system to evacuate, and she said on Saturday that they need to be sheltered in place by midnight. The areas under the evacuation order included the city’s Lake Catherine, Venetian Isles and Irish Bayou areas, the mayor said on Twitter.
“In no way will this storm be weakening, and there’s always an opportunity for the storm to strengthen,” Ms. Cantrell said at a news briefing. “Time is not on our side. It’s rapidly growing, it’s intensifying.”
She added that the city authorities were setting up a shelter for after the hurricane at the New Orleans Ernest N. Morial Convention Center, the same place thousands of evacuees flocked to after Hurricane Katrina.
Collin Arnold, the director of the New Orleans Office of Homeland Security and Emergency Preparedness, warned on Saturday that residents should expect power failures and should have enough food and water to last three days.
Along the Gulf Coast, a hurricane watch was issued for the New Orleans metropolitan area and the area between Cameron, La., and the border of Mississippi and Alabama, where Gov. Kay Ivey declared a state of emergency on Saturday afternoon.
Sunday is the 16th anniversary of Hurricane Katrina’s landfall in the state. That storm unleashed catastrophic floods and blistering winds, producing one of country’s costliest disasters ever.
It has been a dizzying few weeks for meteorologists who monitored three named storms that formed in quick succession in the Atlantic, bringing stormy weather, flooding and damaging winds to different parts of the United States and the Caribbean.
First came Tropical Storm Fred, which made landfall on Aug. 16 in the Florida Panhandle. As Fred moved across the Southeast, it brought heavy rains and touched off several tornadoes. At least five people were killed after flash floods wiped out homes in western North Carolina in the wake of the storm.
And Henri formed on Aug. 16 as a tropical storm off the East Coast of the United States.
It strengthened into a Category 1 hurricane but was downgraded before making landfall in Rhode Island, sparing the region the worst of what had been predicted. It thrashed the Northeast with fierce winds and torrential rain, knocking out power to more than 140,000 households from New Jersey to Maine. Some communities in Connecticut were evacuated and rainfall records in New York City were shattered.
The links between hurricanes and climate change are becoming more apparent. A warming planet can expect to see stronger hurricanes over time, and a higher incidence of the most powerful storms — though the overall number of storms could drop because factors like stronger wind shear could keep weaker storms from forming.
Hurricanes are also becoming wetter because of more water vapor in the warmer atmosphere; scientists have suggested that storms like Hurricane Harvey in 2017 produced far more rain than they would have without the human effects on climate. Also, rising sea levels are contributing to higher storm surges — the most destructive element of tropical cyclones.
A major United Nations climate report released in August warned that nations have delayed curbing their fossil-fuel emissions for so long that they can no longer stop global warming from intensifying over the next 30 years, leading to more frequent life-threatening heat waves and severe droughts. Tropical cyclones have probably become more intense over the past 40 years, the report said, a shift that cannot be explained by natural variability alone.
Ana became the first named storm of the season on May 23, making this the seventh year in a row that a named storm developed in the Atlantic before the official start of the season on June 1.
In May, scientists with the National Oceanic and Atmospheric Administration forecast that there would be 13 to 20 named storms this year, six to 10 of which would be hurricanes, and three to five major hurricanes of Category 3 or higher in the Atlantic. In early August, in a midseason update to the forecast, they continued to warn that this year’s hurricane season would be an above average one, suggesting a busy end to the season.
Matthew Rosencrans of the National Oceanic and Atmospheric Administration said that an updated forecast suggested that there would be 15 to 21 named storms, including seven to 10 hurricanes, by the end of the season on Nov. 30. Ida is the ninth named storm of 2021.
Last year, there were 30 named storms, including six major hurricanes, forcing meteorologists to exhaust the alphabet for the second time and move to using Greek letters.
It was the highest number of storms on record, surpassing the 28 from 2005, and included the second-highest number of hurricanes on record.
Neil Vigdor, Derrick Bryson Taylor, Christine Hauser and Alyssa Lukpat contributed reporting.