In its latest assessment of the impact of the bushfires, the NSW Rural Fire Service said 672 properties had been destroyed since January 1.

That includes at least 380 homes in the Eurobodalla Shire area and 88 in the Bega Valley.

In welcome news, NSW Police confirmed two men who had been missing in the South Coast fires - one at Kiah and one at Lower Towamba - had been found.

A total of 20 people have died in NSW bushfires since early October.

Cooler temperatures and patches of rain have assisted fire crews battling bushfires, which have ravaged the coast and parts of the NSW high country.

Favourable conditions in the ACT also helped local crews control the small Hospital Hill fire in Namadgi National Park. The fire flared on Tuesday, but was quickly contained by aerial and ground crews.

Fire crews will continue to monitor the fire in coming days. Defence is also now on stand-by to help with the fires burning to the southwest of the ACT.

Major General Jake Ellwood said the NSW defence taskforce had told ACT emergency services on Tuesday that it was ready to "provide whatever support they may require in due course".

In NSW, the massive Currowan fire, which has burned through more than 300,000 hectares between Batemans Bay and Nowra, was being controlled on Tuesday night, according to the Rural Fire Service.

The Badja Forest Road fire, inland from Bermagui and Narooma, and the Border Fire, near Eden, continue to burn out of control, although both have been downgraded to advice level.

In the high country, authorities are on high alert amid fears two large out-of-control blazes could merge, creating a fire extending from the Victorian border up through Kosciuszko National Park.

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Friday is set to bring another wave of potentially dangerous bushfire conditions to the Snowy Mountains, with the Bureau of Meteorology predicting warm temperatures and northwesterly winds to pass through the region.

While temperatures on the South Coast are forecast to climb into the 30s on Friday, firefighters aren't expected to have to contend with the hot and dry winds that fanned the blazes on New Year's Eve and January 4.

Canberra was expected to reach a top of 39 degrees on Friday, according to latest forecast from the Bureau of Meteorology.

Authorities have yet to declare a total fire ban for the territory on Friday, but the fire danger on that day will be severe.

Late on Tuesday afternoon, ACT conservator of flora and fauna Ian Walker announced a number of parks and nature reserves across the territory would remain closed until January 20 due to fire risks.

Namadgi National Park, Tidbinbilla Nature Reserve, Mulligans Flat Woodland Sanctuary and Kowen Forest were among 16 parks and reserves to be declared off limits.

Five campgrounds - Woods, Honeysuckle, Orroral, Mount Clear and Blue Range - have been shut for the fire season.

Popular summer swimming spots across the ACT, including Kambah Pool, Pine Island, Point Hut and Uriarra Crossing, will remain open.

Electric barbecues provided at Cotter, Casuarina Sands, Pine Island and in Canberra's suburban parks will be available to the public, however all gas barbecues will be turned off.