Ocean swells could reach 10 to 11 feet, according to Kathleen Bergin, who works in shoreline management for the Delaware Department of Natural Resources and Environmental Control. Winds may also keep water levels elevated, raising the possibility of flooding along back bays.

“Here in Delaware, things that happen two and three hundred miles offshore really are the problem,” Bergin said, explaining that wave energy can take days to reach shore and dissipate. She said officials expect erosion both Monday night and Tuesday.

The risks come as coastal communities are still dealing with damage from the previous storm. In Bethany Beach, most beach access ramps remained closed Monday after waves washed away sand beneath them and cut into sections of dunes.

The rough surf was already affecting people on the water. Windsurfer Stan Iwamoto said he had to abandon his equipment after conditions damaged his sail. “Too rough. Time to quit,” he said.

Although conditions on land appeared relatively calm Monday, officials said offshore storms can generate waves that affect beaches hundreds of miles away. Crews are continuing restoration work, and the latest forecast threatens to set back repairs and further limit access to the shoreline.