Six weeks after Sandy hit New York, lower Manhattan law firms that remain out of their offices are hoping to return by next month but are confronting the possibility it could take much longer.

Harris Beach COO William Kedley said the firm’s initial lease of temporary space at 1290 Avenue of the Americas expires in early January, giving lawyers a few weeks to decide if the firm can return to 100 Wall St. If there’s not enough time, Kedley said the firm has the option to renew.

A big factor in the decision will be whether the telecommunications and data systems are up and running, Kedley said.

Lawyers at Fragomen, Del Rey, Bernsen and Loewy also remain in temporary space and are hoping to return to 7 Hanover Square by early January, but “we just don’t have clarity,” said Michael Patrick, a partner and executive committee member. “We’re also frustrated about not having information” about the building’s condition.

Sandy took out about 95 percent of Verizon’s copper network downtown, Mayor Michael Bloomberg said last week. “They are now rebuilding better and smarter with fiber, but full restoration will take months.”

Verizon’s schedule “right now says that lower Manhattan is not going to be back up until May,” Bloomberg said. “That is just not acceptable.”

He added, “Those buildings in downtown that lost electricity and heat should be back up by the end of this month, but they can’t be occupied unless we have telephone service.”

Meanwhile, Fried, Frank, Harris, Shriver & Jacobson, which had to take temporary space on Park Avenue, moved back on Nov. 27 to One New York Plaza. The firm said it has phone service.

“We all moved back into our offices…and everything went very smoothly. We are happy to be back in our space,” said spokeswoman Patricia Lojo.

Several other downtown law offices were not so fortunate. At Harris Beach’s location at 100 Wall St., member Steven Rice said, “my understanding is that the basement was substantially flooded with salt water and it caused significant damage” to electricity and the connections and wirings necessary for phone and computer service.

“Reestablishing those connections is a step-by-step process” and will take a while, Rice said.

Harris Beach’s offices on the 22th-24th floors didn’t sustain damage, but the firm did have some file storage in the basement, Kedley said. Fortunately, those files were backed up electronically, he said.

Harris Beach had to get new equipment, printers and laptops, Rice said.

“Clearly everyone’s business routine was completely disrupted by that. It’s not a matter of clicking a switch,” he said.

Kedley said the building recently received a green sticker, meaning it’s safe and the building is allowed to resume operations.

“That allows us to get our facilities and IT folks back on the ground in that building,” Kedley said.

And the building was planning to switch back to Con Edison power from generator over the weekend.

“Everybody wants to go back downtown,” Kedley said. “Things are never the same” in temporary space.

Harris Beach has flood insurance and insurance for business interruption, he said, adding “that’s not to say we won’t experience some economic hit for portions of the cost because some things won’t be covered.”

The disruption will ultimately cost the firm at least $50,000, which is the firm’s insurance deductible, he said.

Stroock & Stroock & Lavan is also still out of its downtown offices at 180 Maiden Ln. For now, the firm has rented temporary space at 601 Lexington Ave. and is using its midtown office at 767 Third Ave.

“180 Maiden Ln. was severely flooded and is not operational. We have been told that the building will be out of service for two weeks. We are planning for a longer period,” the firm’s executive committee said in a Nov. 4-dated message on Stroock’s website.

“Our Verizon telephone service has been compromised because of damage to Verizon’s facilities at Broad Street and World Trade Center. We have rerouted our main line to the Los Angeles office, which is relaying calls and messages, though we may experience occasional delays or intermittent connection problems resulting from the damage. We are exploring phone solutions, although it may be some time before normal phone service is restored,” the message said.

Stroock co-managing partner Stuart Coleman and a firm spokesman declined to comment further.

Gordon & Rees, at 90 Broad St., remains temporarily at 1040 Avenue of the Americas. The firm hopes to return the first week of January, said office manager Oria Aponte.

Cahill Gordon & Reindel, at 80 Pine St., had to find temporary space on short notice at 1271 Avenue of the Americas, said William Hartnett, chair of the executive committee. The firm has heard from the landlord that it can return downtown in two weeks, Hartnett said.

For Fragomen, the firm’s temporary arrangement at a portion of Dewey & LeBoeuf’s former office is through April 30.

“If we can move back into our space by the end of December, that would be fantastic,” Patrick said. “Obviously, if it goes on for many more months, it creates secondary issues.”

For example, “You’re talking about not having the kind of access to the files we would normally have.” The firm still has to retrieve files from its downtown office when needed, Patrick said.

But he added, “We’re going to stay optimistic that we’re going to get back in there at the early part of the new year.”