Dave Caron was expecting a rush, so he showed up early Saturday morning to unlock his grocery store in Branford, Conn. Already, 20 people were clustered around the entrance.

By midmorning, the business was so crowded with shoppers stocking up in preparation for Henri that he had to call family to help out. His wife and son came. So did his sister, who made the 30-mile drive down from Middletown, Conn.

“It still wasn’t enough,” Caron said.

An unending stream of customers was clearing shelves of ice, bottled water, deli meats, batteries and other goods. “My parking lot has been full since the moment I opened,” he said. “It’s been more business than we could possibly handle.”

People across coastal New England and Long Island scrambled to make last-minute preparations ahead of what is expected to be the region’s worst storm in 30 years. Though Henri slightly weakened from a hurricane to a strong tropical storm Sunday, forecasters still anticipate it will pack a punch with strong winds and flooding. Across parts of Connecticut, Rhode Island and on Long Island, heavy rain was falling by daybreak.

Worried residents boarded windows and loaded shopping carts with essentials. Some tied down boats. Many lined up at gas stations to fill canisters of fuel for generators.

New York Gov. Andrew M. Cuomo (D) issued warnings about a storm and took questions about the timing of his transition from office in an Aug. 21 news conference. (New York Governor's Office)

Connecticut Gov. Ned Lamont (D) declared a state of emergency ahead of the storm. “We’re anticipating heavy rainfall and high winds, with coastal and urban flooding a significant concern,” he tweeted Friday. He added that residents should expect to shelter in place by Sunday afternoon through at least Monday morning.

Utilities in the state told customers to prepare for a loss of power for five to 10 days. Officials were also urging evacuations in some low-lying areas, including parts of New Haven.

“We have not seen anything of this magnitude for many years,” said New Haven Emergency Management Director Rick Fontana. “This is a dangerous storm.”

Massachusetts Gov. Charlie Baker (R) said on Aug. 20 that Tropical Storm Henri is forecast to become a hurricane and slam southern New England. (Reuters)

It’s been 10 years since hurricane warnings were last issued for the Northeast, where Irene came ashore as a tropical storm in August 2011. If Henri did make landfall at hurricane strength, it would be the first storm to do so in the Northeast since Bob in 1991.

A voluntary evacuation order was in effect for Fire Island, N.Y., where ferry service was ordered suspended Sunday. Residents should leave “for their own safety,” said Suffolk County Executive Steve Bellone. More than a dozen other New York counties also were under states of emergency.

In Mystic, Conn., Matt Butcka was readying his house for potential flooding and an extended stretch without electricity.

He lives near the mouth of the Pawcatuck River, in an area with little elevation, and he isn’t taking any chances. He layered sandbags around the openings to his basement and brought out two sump pumps to keep the water levels down. His generator is gassed up, and the cooler is filled with ice.

If the wind gets bad, he’s got fresh plywood cut for the windows. “If they blow out we’ve got something to cover them with,” Butcka said. Now, he said, “we’re filling up as many containers as we can with water.”

“Residents should start preparing for power outages and coastal flooding,” tweeted Laura Curran, executive for Nassau County on Long Island. “Our crews will be working around-the-clock.”

In Huntington, N.Y., on Long Island’s bayside, Gina DeMaio was trying to get through as much work as possible at her job at a realty group before hunkering down with her husband and her two dogs, Ruby and Sophie. She canceled all her open houses for Sunday, then went home to tie down her patio furniture.

“You never know,” she said. “At the last minute it could turn out to be another Hurricane Sandy. Or it could be another tropical storm and not cause as much damage as they expect.”

On the eastern side of Long Island, Raffaele Franzese was planning to wrap up a frenetic day working at a local supermarket, then head home to his three-bedroom ranch in Shirley, N.Y. His cars were full of gas, he has plenty of water, and the kitchen was stocked with nonperishables. He wasn’t worried, he said.

“Tonight when I go to bed I’ll say a nice little prayer and hope the good Lord watches over everybody,” Franzese said. “It’s out of our hands now. It’s mother nature.”

In New York City, the “Homecoming Concert,” a star-studded event in Central Park billed as a celebration of the city’s recovery from the coronavirus pandemic, was interrupted by the deteriorating weather, with New York police tweeting that concertgoers should “calmly move to the nearest exits and proceed to areas outside of the park.”

The highly promoted show featured Bruce Springsteen, Paul Simon, Jennifer Hudson, Carlos Santana, LL Cool J and others, the Associated Press reported.

The National Hurricane Center has warned of a potentially life-threatening storm surge, or storm-driven rise in ocean water above normally dry land. Making matters worse, tides are running high due to Sunday’s full moon.

Flash flooding could also be widespread, with more than half a foot of rain expected in Long Island and areas east of the Berkshires in western New England. That comes following what was the wettest July on record for many cities in the Northeast. The Weather Service cautions of a “moderate risk” of flash flooding and excessive rainfall, “with isolated maximum totals near 10 inches” probable.

At Caron’s Corner in Branford, Caron said he planned to stay open until about noon Sunday, then tape up the grocery store windows and hope for the best. At home, he’s going to fill up eight five-gallon gas cans with fuel — enough to run his residential generator for about a week.

His business is just two miles from the Long Island Sound and blocks away from an inlet that snakes through town. Heavy storms last year knocked out electricity for a week, causing him to throw out $100,000 worth of food, he said. Superstorm Sandy had cost him business too when it struck in 2012.

This time around, he’s keeping less inventory. Whatever meats, ice creams and other perishables are leftover when he shuts down Sunday are going into the freezers, which he hopes will stay powered.

“I feel good about the way business is, but nervous about what I’m looking at losing,” Caron said. “Been there, done that.