NSW residents have been urged to move cars under cover and clear out their backyards as the state prepares to be battered by winds up to 120km/h on Wednesday afternoon.

A severe weather warning has been issued for far western NSW and other parts of the state including Newcastle, Wollongong, Nowra, Batemans Bay, Goulburn, Broken Hill and Thredbo Top.

In Sydney, the Cooks River is expected to peak at 1.3m on Wednesday evening, resulting in minor flooding in the city's inner west.

A flood warning has been issued for Tempe with abnormally high tide expected to cause flooding at the Tempe Bridge.

Streets in Marrickville may also be affected by "dangerous floodwaters" during high tide at around 8pm.

Helen Reid, from the Bureau of Meteorology, said the Sydney metropolitan area will remain slightly sheltered from the vigorous winds however there had already been several reports of damages.

"We've seen winds averaging right across the basin of about 40km/h, there have also been some gusts reported that were just over 70km/h," she said.

"The Sydney basin is a little bit sheltered from those extra strength winds, but we are still definitely feeling the edges of it.

"These winds are expected to continue through to Thursday, possibly easing off during the course of tomorrow, we do have another cold front expected to set in on Friday and Saturday however the winds aren't likely to be as strong.

"We will be watching to see if it requires any warnings."

In the state's alpine areas, wind speeds are expected to average from 80 to 90km/h, with peak gusts reaching up to 120km/h on Wednesday.

Parts of the NSW coast and ranges between the Barrington Tops and the Southern Alps will see winds between 60 and 70km/h and gusts in excess of 90km/h.

The windstorm is also expected to skim a few degrees off the temperature, with the Bureau of Meteorology encouraging people to consider adding an extra layer of clothing.

The threat of severe winds is expected to ease for far western NSW on Wednesday afternoon and for eastern NSW during Thursday, although conditions will remain very windy in both areas.

Flooding is also expected at St Georges Basin at Sussex Inlet on Wednesday and Thursday evenings, due to an "abnormally high tide".

Elsewhere in the state, the RFS is working hard to get control of a bushfire burning at Duranbah, less than an hour north of Byron.

The Daily Telegraph understands the fire started from a landowner doing their own hazard reduction burning, or 'pile burning'.

The fire became out of control as it spread through the grassy vegetation. Crews from Murrwillumbah, Tweed and other local brigades are fighting to establish containment lines around the blaze.

The RFS said the fire wasn't posing an immediate threat to homes, but an advice level warning is in place. The 20ha blaze is burning at the Pacific Hwy and Clothiers Creek Rd. Locals in the area of Forest Hill Rd and Tanglewood should monitor conditions, listen to fire fighters and prepare to follow their bushfire survival guide.

RFS spokesman Greg Allan said the fire was "unique". "North-westerly winds are pushing in a south-easterly direction, but the fire is actually burning back onto the wind," Mr Allan said.

"That's why areas to the north and south should monitor the fire in case conditions change," he said.

Mr Allan said it was a good reminder to land owners to always notify neighbours and fire authorities when preparing to conduct pile burning.

Originally published as Wild winds to lash NSW, Sydney suburbs brace for flooding