Residents of Lord Howe Island have endured a terrifying night as ex-tropical Cyclone Uesi whipped up 150kph winds, ripping down trees and damaging buildings and boats.

Key points: Authorities are assessing possible damage to houses

Authorities are assessing possible damage to houses The ex-cyclone is moving towards the Tasman Sea

The ex-cyclone is moving towards the Tasman Sea Dangerous winds are likely to persist on the island for several hours

The cyclone passed straight over the top of the island, which is 600km off the NSW coast, and is now weakening as it moves towards the Tasman Sea.

Homes were damaged and at least one boat was capsized off the western edge of the island.

As gales roared through, felling Norfolk Pines up to 25 metres tall, the island's 400 permanent residents and another 400 tourists bunkered down.

They spent the night keeping up to date with emergency information — a difficult task with no mobile phone reception and very little internet.

Islanders and tourists did what they could to prepare for the wild night. ( ABC News: Jonathan Hair )

On the eastern side of Lord Howe, the storm sparked dangerous surf conditions, and the Bureau of Meteorology (BOM) predicted 14m swells.

Local Yolantee Eeles had to rescue several White Terns, which breed on Lord Howe Island, as the storm brought down the Norfolk Island Pines they nest in.

Ms Eeles transported the birds home on her bike where she will nurse them back to health until the storm completely subsides.

"Any that have fallen out of the trees … we'll take them home and feed them fresh fish until they recover," Ms Eeles said.

"One's got a broken wing and is bleeding from underneath the wing. [But] there's two little chicks that are in pretty good shape so they've got a chance."

Ms Eeles shows off the White Terns she saved after the storm. ( ABC News: Jonathan Hair )

The birds, whose nest was destroyed, will be nursed back to health. ( ABC News: Jonathan Hair )

Nicola Fuller, who lives on the island, had three large branches sticking through her bathroom walls in the wake of the wild weather.

"It happened in the pretty early hours of the morning, so I wasn't brushing my teeth then," she said.

She said the island had a lot of damage.

"I haven't gone for a walk too far, it's looking pretty overturned."

Ms Fuller's bathroom sustained plenty of damage when the ex-cyclone hit. ( ABC News )

A man fixes a fence on the island which was damaged in the wild weather. ( ABC News: Jonathan Hair )

The storm did not deter some visitors like James Eldridge and Julie Bassett, who came to the island to soak up its natural beauty.

"I think it's fairly exciting to be here at this time," Ms Bassett said.

"It makes the whole visit more spectacular obviously, with all the waves and the wind and the atmosphere," Mr Eldridge said.

"Any of these big natural events you've got to respect because they can be life threatening if you're in the wrong place," he said.

Julie Bassett and James Eldridge are on holiday but said the cyclone was "exciting" to watch. ( ABC News: Jonathan Hair )

The storm is moving away from the island but residents have been warned to stay vigilant.

State Emergency Services (SES) volunteers are preparing to start the clean-up, but the BOM has warned damaging winds could persist for several hours.

The cyclone was downgraded yesterday afternoon but maintained an intensity equivalent to a category two tropical cyclone into the evening.

An arborist chainsaws a 80 foot Norfolk Pine which fell in the storm. ( ABC News: Jonathan Hair )

ABC weather expert Graham Creed said the downgrade took place because a tropical cyclone relies on the water temperature being above 26.5 degrees.

"Once a tropical cyclone moves over waters that are colder than that, it transitions to a more general low pressure system, but it still maintains very strong conditions," he said.

"Where a cyclone is quite symmetrical in the damage that it will cause, a low pressure system, as it moves further south, will actually cause the worst of the conditions."