BATON ROUGE, LA. -- Francine became a hurricane Tuesday evening as it barreled toward south Louisiana, strengthening over extremely warm Gulf waters as those in possible harm's way rushed to complete storm preparations, filling sandbags, buying gas and stocking up on necessities for an expected landfall in the coming day.

Residents, especially in south Louisiana, have a 24-hour window to “batten down all the hatches,” Louisiana Gov. Jeff Landry warned at midday while Francine was still a tropical storm.

The freshly minted Category 1 hurricane packed top sustained winds of 75 m.p.h. (120 kph) and forecasters warned it was expected to crash ashore Wednesday afternoon or evening in Louisiana with a potentially life-threatening storm surge and damaging winds — perhaps even as a Category 2 storm with winds of 96 to 110 m.p.h. (155 to 175 km/h).

Ahead of the storm's approach, lifelong New Orleans resident Roxanne Riley, 42, gathered water, snacks and other food from a Walmart and said she planned to stay at a family member’s house on high ground to avoid flooding. But she was ready to evacuate if things got worse.

“It’s very frustrating every time a storm comes in,” Riley said. “I’ll just make sure my car is ready to roll in case I need to go by tomorrow. I’m going to keep on checking to see what it’s looking like.”

By 8 p.m. ET Tuesday, Francine was centered about 350 miles (560 kilometres) southwest of Morgan City, La., and was moving northeast at 10 m.p.h. (17 km/h), the Miami-based National Hurricane Center said in an advisory.

A hurricane warning was in effect along the Louisiana coast from Cameron eastward to Grand Isle, about 50 miles (80 kilometres) south of New Orleans, according to the center. A storm surge warning stretched from the Mississippi-Alabama border to the Alabama-Florida border Such a warning means there’s a chance of life-threatening flooding.

Once Francine makes landfall, Landry said, residents should stay in place rather than venturing out onto the roads and risk blocking first responders or utility crews working to repair power lines.

Helping Francine gain hurricane status Tuesday night were the Gulf's exceedingly warm late-summer waters. Water temperatures are about 87 degrees (31 degrees Celsius) where Francine is located, said Brian McNoldy, senior research associate at the University of Miami's Rosenstiel School of Marine, Atmospheric, and Earth Science.

“The ocean heat content averaged over the entire Gulf is the highest it’s been on record for the date," McNoldy wrote on his blog.

In downtown New Orleans during the day, cars and trucks were lined up for blocks to collect sandbags from the parking lot of a local YMCA. CEO Erika Mann said Tuesday that 1,000 bags of sand had already been distributed by volunteers later Tuesday to people hoping to protect homes from possible flooding.

“I love that these are community people that came out,” Mann said. “It’s a beautiful effort to do what we do in New Orleans, we’re resilient and we come together to help in the times we need each other.”

Hurricane Francine sand bags

One resident picking up sandbags was Wayne Grant, 33, who moved to New Orleans last year and was nervous for his first potential hurricane in the city. The low-lying rental apartment he shares with his partner had already flooded out in a storm the year before and he was not taking any chances this time around.

“It was like a kick in the face, we’ve been trying to stay up on the weather ever since,” Grant said. “We’re super invested in the place, even though it’s not ours.”

A little over three years after Hurricane Ida trashed his home in the Dulac community of coastal Louisiana’s Terrebonne Parish – and about a month after he finished rebuilding – Coy Verdin was preparing for another hurricane.

“We had to gut the whole house,” he recalled in a telephone interview, rattling off a memorized inventory of the work, including a new roof and new windows.

Verdin, 55, strongly considered moving farther inland, away from the home where he makes his living on nearby Bayou Grand Caillou. After rebuilding, he said he’s there to stay.

“As long as I can. It’s getting rough, though,” he said. He was preparing to head north to ride out Francine with his daughter in Thibodaux, about a 50-minute drive away. “I don’t want to go too far so I can come back to check on my house.”

Landry said the Louisiana National Guard is being deployed to parishes that could be impacted by Francine. They are equipped with food, water, nearly 400 high-water vehicles, about 100 boats and 50 helicopters to respond to the storm, including possible search-and-rescue operations.

Francine is the sixth named storm of the Atlantic hurricane season. There’s a danger of life-threatening storm surge as well as damaging hurricane-force winds, said Brad Reinhart, a senior hurricane specialist at the hurricane center.

There’s also the potential for four to eight inches (10 to 20 centimetres) of rain with the possibility of 12 inches (30 centimetres) locally across much of Louisiana and Mississippi through Friday morning, Reinhart said. That heavy rainfall could also cause considerable flash and urban flooding.

The hurricane center said eastern Mississippi and especially coastal parts of Mississippi, Alabama and the Florida Panhandle were at risk of “considerable” flash and urban flooding starting Wednesday. It said flooding was also “probable” further inland into the lower Mississippi Valley and lower Tennessee Valley from Wednesday through Friday as a disbanding Francine churns inland.

Francine is taking aim at a Louisiana coastline that has yet to fully recover since hurricanes Laura and Delta decimated Lake Charles in 2020, followed a year later by Hurricane Ida. Over the weekend, a 22-story building in Lake Charles that had become a symbol of storm destruction was imploded after sitting vacant for nearly four years, its windows shattered and covered in shredded tarps.

Francine's storm surge on the Louisiana coast could reach as much as 10 feet (three metres) from Cameron to Port Fourchon and into Vermilion Bay, forecasters said.

“It’s a potential for significantly dangerous, life-threatening inundation,” said Michael Brennan, director of the hurricane center, adding it could also send “dangerous, damaging winds quite far inland."

He said landfall was likely somewhere between Sabine Pass — on the Texas-Louisiana line — and Morgan City, La., about 220 miles (350 kilometres) to the east.

Associated Press writers Curt Anderson in St. Petersburg, Florida, Kevin McGill and Jack Brook in New Orleans contributed to this story