Residents of Lord Howe Island are bracing for 14-metre waves, destructive winds and up to 150mm of rain as Cyclone Uesi continues tracking straight for the island.

Key points: Wind gusts up to 150kph are forecast for Lord Howe Island

Wind gusts up to 150kph are forecast for Lord Howe Island The system is expected to weaken later today

The system is expected to weaken later today Strong winds and large swells expected to impact mainland NSW

The category-two cyclone is expected to weaken as it reaches the tiny island tonight, which is 600km off the NSW coast.

It was downgraded on Thursday afternoon from a tropical cyclone to an ex-tropical cyclone, but is still expected to maintain an intensity equivalent to a category 2 tropical cyclone

There are also about 400 tourists on the island in addition to 400 residents, and plans are being made to manage those unable to leave if flights are cancelled.

"It's still a reasonably serious weather system and we are taking appropriate action to prepare for that," Lord Howe Island Board chief executive Peter Adams said.

The Bureau of Meteorology (BOM) said around 6:00pm the island recorded 102kph winds, with expected gusts up to 130kph and swells of about 5 metres.

"The community are in a good position to be ready for this system, but we need to stress the destructive winds and very dangerous surf conditions pose the biggest issue," BOM forecaster Mike Funnell said.

"It's not out of the question that Lord Howe Island will experience winds of 155kph which is quite extraordinary."

Mr Funnell said Lord Howe Island is only hit by destructive winds of around 120kph every 10 years.

The cyclone is expected to pass directly over the island early on Friday morning, with damaging winds and flash flooding likely.

"The fact this system is tracking right over the top of the island gives us pause to consider just how great the impacts will be," Mr Funnell said.

Boats line a beach on Lord Howe Island in stormy conditions last year. ( ABC News: Mridula Amin )

A Qantas spokesperson said today's flights were unlikely to be impacted, and that the airline had not yet made a decision about tomorrow's services.

Mr Adams said precautions included getting earth-moving equipment in place to allow the openings of flooded creeks, clearing roadside drains and the "renourishment" of areas impacted by coastal erosion.

Accommodation on the island is at capacity and authorities are attempting to make sure everyone has a bed.

"All things being equal, the people that can't get off the island are cancelled out to some degree by ones that can't return here, but there's a lot of adjustment that goes on to accommodate those people," Mr Adams said.

Josh, who lives on Lord Howe Island, said he could see Uesi approaching and was preparing to "batten down the hatches".

"Everyone's just kind of getting ready, it's getting pretty eerie and overcast here already but I don't think it's going to be anything too serious until tonight," he said.

"I'm a plumber, so I've got a pretty busy day getting everyone ready."

There are hundreds of tourists on Lord Howe Island at the moment. ( ABC News: Mridula Amin )

Mr Funnell said the system would not impact the NSW mainland.

"It can still have quite considerable impacts though, we're expecting the sort of impacts onto Lord Howe Island that you would normally see from a category one or possibly a category two system."

Mr Adams said the island, which was isolated and without mobile phone coverage, "organises itself differently".

"People live close to each other, they're very connected and they're very experienced in this," he said.

"The SES [State Emergency Service] have been meeting with all the other emergency services, so the usual emergency response agencies are here — it's just that they're all volunteers from a very small community."

Large swell and strong winds will impact the NSW coastline. ( Twitter: @dezomopr )

While the cyclone won't hit the NSW coast, it is expected to produce large swells, high tides and strong winds over the weekend.

"This will further erode the beach system ... [which] changed in shape last week," Mr Funnell said.

A large inland trough will also continue to bring storms and potentially heavy rain to large parts of the state over the coming days with isolated falls as heavy as 50mm in some areas.