An out-of-control bushfire will likely burn for weeks, but the threat from another has been downgraded after the destruction of a popular wedding venue and conference centre.

Firefighters are battling two uncontrolled bushfires, one at Dimboola and Wail near the South Australian border and the other in the south-western part of the Grampians National Park.

The Dimboola fire was sparked by dry lightning at Little Desert National Park on Monday and had already grown to 63,000 hectares, State Control Centre spokesperson Luke Heagerty said.

Residents were told to evacuate but some at Dimboola District Hospital and the town’s aged-care home didn’t manage to get out in time and had to shelter in place.

About 190 people sought refuge at a makeshift relief centre in Horsham, with 27 staying overnight.

“The fire grew to such a size and was carrying such energy with it yesterday that it made it quite difficult for any containment,” Heagerty said.

The fire was downgraded to watch and act on Tuesday afternoon and Emergency Management Commissioner Rick Nugent said it would soon be deemed “safe to return”.

“I’m incredibly thankful that no lives have been lost from this fire, and we have no reports of injuries either,” he said at the State Control Centre in Melbourne.

A popular wedding and conference centre, Little Desert Nature Lodge, was destroyed in the blaze.

“The lodge just exploded, it’s totally gone,” Hindmarsh Shire Council mayor Ron Ismay said.

“It’s very sad, it was a great venue for people of the area and it was used for weddings and conferences and meetings and all sorts of stuff.

“It’s a big loss to the community”.

Nugent confirmed a farm house west of Dimboola was also lost and another near a river may have been impacted.

Little Desert National Park and Wail State Forest remain closed and the rain line between Victoria and SA has been suspended.

Damage assessments were expected to continue throughout Tuesday.

A second emergency warning issued for Strachans, Victoria Point and Victoria Valley in the Grampians National Park has also been downgraded to watch and act.

The fires are in the remote south-west and north-west parts of the Grampians that were not scorched by fires earlier this summer.

“It’s incredibly dry in there,” Nugent said.

“It’s been a lot of years since parts of the Grampians has burnt, and with all of those conditions, it’s just made it really challenging this year for us.”

It took 21 days to bring blazes in the Grampians, sparked on December 17, under control.

Forest Fire Management Victoria chief fire officer Chris Hardman said these fires would present a “similar scenario” as a cool change gave way to gusty conditions.

“The Grampians fire will be a real challenge for the coming days and potentially weeks,” he said.

Victorian Premier Jacinta Allan said there were up to 150 fires across the state as high heat and winds brought dangerous conditions and fire bans.

A volunteer firefighter protecting the community on Monday had their ute stolen from Werneth Fire Station, about 60 kilometres west of Ballarat. It was last seen at Linton.

“I can’t think of anything worse or a lower act to go and steal a car of a volunteer,” CFA chief officer Jason Heffernan said.

Heatwave, late change could bring carnage

While a cool change has brought more mild weather to Australia’s south, much of NSW can expect scorching temperatures on Tuesday.

After peaks in the high 30s or low 40s, an afternoon cool change will bring the risk of severe thunderstorms, including large hail and damaging winds.

That follows similarly strong storms on Monday night, which resulted in 211 call-outs for the NSW State Emergency Service, mostly in metropolitan Sydney.

“The majority of incidents were for trees down onto properties and powerlines after strong winds swept through the east of the state … while [Tuesday] is hot, we are anticipating more afternoon thunderstorms with strong winds,” a spokesperson said.

NSW Rural Fire Service inspector Ben Shepherd warned of a “vast area of high fire danger”, particularly after a staggering 140,000 lightning strikes in the 24 hours to 7am.

The Australian Energy Market Operator has issued its lowest-tier warning for power supplies in NSW on Tuesday afternoon, encouraging industry participants to lift output to meet expected demand.

BOM senior meteorologist Miriam Bradbury said a “southerly buster” would bring a sharp drop in temperatures in NSW on Tuesday afternoon and evening.

“A southerly buster is a strong and cool wind which moves up from the south to the north, it is forecast to reach Sydney around 4pm this afternoon, at which time the temperature could drop up to 15 degrees in 15 minutes,” she said.

The change should bring strong winds and could also spark potentially severe thunderstorms, mostly around the eastern ranges and out towards the east coast.

-with AAP