Persistent heatwave conditions fuel bushfire threat

Dangerous fire conditions are set to continue across parts of eastern Australia as forecast dry lightning risks new blazes.

Severe heatwave conditions are lingering in NSW, spanning eastern parts of the state and extending from the Hunter to the south coast.

More than a dozen homes and shacks, outbuildings and cars were damaged and two firefighters were injured fighting an out-of-control fire at Dolphin Sands on Tasmania's east coast on Friday.

Crews in Tasmania are continuing to investigate its cause as they deploy air and ground tankers to contain the fire which has burnt more than 700 hectares.

While the fire is at watch and act level, Tasmania Fire Service has urged people not to return.

"Emergency services and contractors are currently going through areas of the fireground to make it safe and assess the damage that has been caused," Commissioner Jeremy Smith said.

Some residents will be without power for a week after TasNetworks confirmed severe fire damage to dozens of power poles in the Dolphin Sands area.

But cooler temperatures and showers washing across the state on Saturday will likely bring relief to fire crews.

NSW residents will swelter in well above-average temperatures on Saturday, with the mercury peaking at 37C in Sydney and nudging the low 40s in western suburbs, the Bureau of Meteorology said.

An emergency warning for residents near Beni Road, outside Dubbo, was downgraded, as was the bushfire at Bulahdelah on the mid-north coast, on Friday evening after easing conditions helped firefighters gain the upper hand on the fires.

Total fire bans are in place for large parts of NSW, including inland, eastern and northern parts, Sydney and the Illawarra on Saturday.

Thunderstorms forecast across much of southeast Australia brought the risk of dry lightning sparking new blazes, meteorologist Jonathan How said.

Temperatures are expected to ease on Sunday.

Victorians faced milder temperatures as a cold front and thunderstorms wash over after hot, dry, windy weather on Friday.

Firefighters were working to contain a bushfire in Markwood, 280km northeast of Melbourne, which has affected at least three properties.