Bushfire battles all but won as summer dials up threat

Firefighters have gained the upper hand on a fast-moving blaze that destroyed a dozen homes as leaders warn against complacency ahead of an ominous bushfire season.

About 76 bush and grass fires were burning in NSW on Sunday following earlier extreme heatwave conditions.

The threat has eased from an out-of-control bushfire in Koolewong, not far from built-up areas on the Central Coast, that destroyed at least 12 homes on Saturday.

Another four homes were lost further north at Bulahdelah on the Mid North Coast.

The Koolewong blaze was downgraded from watch and act to advice just after midday on Sunday as strong winds gave way to a cool change.

NSW Premier Chris Minns travelled to the bushfire-hit area earlier in the day, speaking to families who had lost their homes in the lead-up to Christmas.

"They were able to get as much as they possibly could in the car and evacuate in a short space of time," he told reporters at Gosford RSL Club's makeshift emergency evacuation centre.

The RSL has been "inundated" with phone calls from locals wanting to donate food, toiletries, nappies and, in some cases, their homes as crisis accommodation, Mr Minns said.

A fire at Milsons Gully, west of Muswellbrook, has scorched more than 11,050 hectares and another at Redhead, south of Newcastle, burned at emergency level on Sunday morning before the threat was lowered to watch and act.

Federal and state disaster assistance funding has been activated across the Central Coast, Mid Coast, Upper Hunter, Muswellbrook, Warrumbungle and Dubbo.

More than 250 firefighters, 50 trucks and nine aircraft battled the Koolewong blaze at its peak.

Several firefighters experienced heat exhaustion and there were reports of minor injuries to civilians.

Other properties and outbuildings were damaged beyond the 12 homes destroyed, with confirmation of losses expected later on Sunday.

NSW Police investigators and the Rural Fire Service were working simultaneously to determine the cause of the blaze, which started at the back of properties on Nimbin Rd.

RFS Commissioner Trent Curtin said a falling ember led to the fire jumping 1km into the Woy Woy Bay area.

"This is an example of what we might see through the upcoming summer season," he said.

The Bureau of Meteorology told NSW emergency service heads last week to brace for a very challenging bushfire season as a result of hot winds and a warmer Pacific Ocean in December, Mr Minns said.

"We can't set in stone what summer will look like," he said.

"Because of uncertain weather predictions, it's incredibly important you expect the unexpected."

Tasmanian authorities have confirmed a blaze at Dolphin Sands, near Freycinet National Park on the state's east coast, was contained after 8mm of overnight rain.

Nineteen homes and shacks, 15 outbuildings and four vehicles were damaged in the fire sparked in the seaside community on Thursday.

Two excavators were creating a firebreak on Sunday but it remained unsafe for residents or vehicles to enter the area.

Tasmanian Premier Jeremy Rockliff was hopeful home and shack owners would be able to return to their properties in coming days, with six applications submitted for short-term hardship grants so far.

"We will look at other measures should they be asked for," he said.

The blazes in NSW and Tasmania, as well as others in Western Australia's Kimberley and Pilbara regions, foreshadowed a "difficult season", Prime Minister Anthony Albanese said.

"NSW, in particular, has a range of pre-conditions ... for being quite a difficult one," he told ABC's Insiders.

Temperatures are expected to ease from Sunday for most of NSW and southern Australia, though the heat will build across northern Australia and WA and return to much of the country early in the week.