Homes have been lost to a dangerous fire front that has threatened NSW coastal towns and triggered emergency warnings before being downgraded after a cool southerly change overnight.

Communities and holidaymakers on the state’s south coast endured a nervous night as flames threatened homes around Barragga Bay and was at emergency level at Coolagolite in Bega Valley.

A shift in the weather about midnight brought some rainfall that eased conditions across Coolagolite.

However, authorities said an unknown number of homes had already been lost.

NSW Rural fire Service commissioner Rob Rogers said the fire was still active but that crews would try to assess the damage on Wednesday.

“We know we’ve lost some homes down there we’re just not quite sure on numbers yet,” he told the Seven Network.

“There are a lot of hidden homes in there so we just need to go in there.

“The good news is there are no reports this morning of people missing so that’s a good sign.”

The RFS has also warned that Wednesday remains another day of danger, with fears the changing winds could push the blaze towards the coastal town of Bermagui.

“People in Bermagui who do not feel adequately prepared to defend their properties should consider relocating to a safer place such as Bega or Narooma before nightfall,” it said, noting towns with open evacuation centres.

Firefighters were still trying to slow the spread on Wednesday morning.

A threat has eased at Coolagolite on the NSW south coast. Photo: NSW RFS

Sweltering conditions on Tuesday, which peaked at 37.2 degrees at Sydney Airport about 2.30pm, sparked dozens of fires across the NSW.

At midnight Tuesday, there were 73 fires burning across the state, with 18 not yet contained.

Tweet from @NSWRFS

Vic flood warnings

In Victoria, flood warnings were issued on Wednesday morning for communities in the state’s east.

The wet reprieve has been welcomed by firefighters, with up to 60 millimetres tipped to fall on fires at Briagolong and Loch Sport on Wednesday, adding to Tuesday’s deluge.

But areas still reeling from bushfires in Gippsland could be cut off if forecast heavy rain causes rivers to swell.

Residents have been warned to keep an eye on rising river levels and be aware of the potential for flash flooding.

There is a major flood warning for Macalister River, with major flooding likely at Licola, 250 kilometres east of Melbourne, from Wednesday morning.

Up to 140 millimetres of rain fell in the 24 hours to 4am Wednesday across the Macalister River catchment, causing rapid river level rises.

“Further rainfall is forecast for the next few days, with a further 60-90 millimetres possible. This situation is being closely monitored, and warnings will be updated as necessary,” Vic Emergency said.

“Major flooding is likely along the Macalister River upstream of Lake Glenmaggie.

“The Macalister River at Licola is currently at 2.85 metres and rising quickly, with minor flooding.

“The Macalister River at Licola is expected to exceed the moderate flood level (3.20 metres) around 05am Wednesday. The river level is likely to reach the major flood level (3.60 metres) around 08am Wednesday. Further rises are possible with forecast rainfall.”

Tweet from @vicemergency

Victorian State Emergency Service chief operations officer Tim Wiebusch urged anyone in the state’s east to stay on top of warnings.

“There’s so many communities that will be at risk of local isolation between 12-24 hours, too many to mention here, but particularly in the north-east and also in that central to eastern part of Gippsland,” he said.

Wiebusch said residents should secure loose objects around their homes, including outdoor settings and trampolines, because they could become projectiles in wild weather.

“There’s certainly an increased risk any time we see large fire scars in the landscape, followed by heavy rainfall,” he said.

“There is the risk of increased debris flow and also localised landslides, particularly in the steeper terrain across Gippsland where some of those fires have not only been in recent days but also over the last couple of years.”

A low-pressure system was expected to form over eastern Victoria and bring up to 100 millimetres of rain over the Eastern Ranges, Bureau of Meteorology meteorologist Christie Johnson said.

“We are still expecting damaging wind gusts to be on the cards so there is that potential for gusts up to 90km/h or even a little bit higher,” she said on Tuesday.

A minor flood warning has also been issued for the Goulburn River, Yarra River and Seven and Castle Creeks.

Weather conditions are expected to ease from Thursday. But flooding may last last until the weekend.

The flood threat comes after many residents in Gippsland were put on alert for fires.

About 700 firefighters spent three days battling two blazes, with one home lost in Briagolong but no reports of serious injuries. The cause of that blaze, which grew to about 17,500 hectares, is under investigation.

-with AAP