Though Isaac's timing is drawing inevitable Katrina comparisons, scientists and storm-savvy Gulf residents don't see the hurricane as the second coming of Katrina, which devastated New Orleans and the Mississippi coast.
Rated a Category 1 hurricane—with wind speeds of at least 75 miles an hour (120 kilometers an hour)—Isaac is no lightweight, having already killed 22 in the Caribbean.
The hurricane is also expected to cause significant damage on the Gulf Coast, dumping as much as 20 inches (50 centimeters) of rain on parts of Louisiana. New Orleans in particular could see winds up to 75 miles an hour, which could fel trees and contribute to widespread power outages.
Even so, Isaac and Katrina are "not even comparable, as far as intensity," said Gavin Phillips, a meteorologist at the National Weather Service's New Orleans/Baton Rouge Weather Forecast Office in Slidell, Louisiana.
"There's the déjà vu thing with the date, but they're not even close."
Coming ashore as a Category 3—with winds between 111 and 130 miles an hour (179 and 209 kilometers an hour)—Hurricane Katrina killed about 1,800 people in the U.S. and caused about $108 billion in damage. (See "Hurricane Katrina: The Essential Time Line.")
By contrast, Isaac is expected to peak with winds no stronger than 95 miles an hour (153 kilometers an hour)—significantly shy of major-hurricane status.
Phillips said a key reason Isaac hasn't intensified more is because the storm had encountered dry air—a momentum killer for hurricanes.
Isaac Faces Stronger New Orleans
"People are a little anxious, but not frightened," said John Young, president of Jefferson Parish, part of metropolitan New Orleans.
Billions of dollars, Young noted, have been spent to strengthen New Orleans's levees, which famously fell during Hurricane Katrina, leading to catastrophic flooding (interactive New Orleans levee map).
"I'm confident the levees are repaired," he said.
Also, new, powerful pumps and floodgates have been installed to move and divert floodwater, he added.
"There's been a tremendous increase in protection."
Still, Young said, the levees currently should withstand only a Category 3 hurricane—Katrina's strength. (Get the story behind the hurricane scale.)
Billions more would have to be spent to save the city from a storm like 1969's Hurricane Camille, a Category 5 that made landfall in Mississippi with winds approaching 200 miles an hour (322 kilometers an hour).
Today, chastened Gulf Coast residents are keeping a wary eye on Isaac. But, like many meteorologists, some residents see little to compare this storm to Katrina. (See "Hurricane Katrina Pictures: Then and Now, Ruin and Rebirth.")
"We went yesterday to get supplies, and we got our house boarded up," Feyh said. "Because of Katrina, everybody's [getting ready] earlier than usual—the batteries were sold out at Walmart."
Alton Cook, who has lived in New Orleans for 50 years and owns a bookstore in the French Quarter, has weathered many hurricanes. He's not taking Isaac lightly, but he's not leaving either.
Before Katrina, "a hurricane was something you went through and never thought too much about," he said. "People who stayed through Katrina didn't expect it to be much different, until the levees broke, and that changed the world."
Willie Drye has been writing about hurricanes and other topics for National Geographic News since 2003. Visit his blog, Drye Goods.