Cooler weather helped firefighters Friday as they battled an unpredictable blaze which has destroyed at least 37 properties, including a historic house.

Scores of residents were evacuated from communities near the tourist township of Margaret River, a coastal area known for its wines in Western Australia, as flames soared as high as 30 metres (100 feet) Thursday.

"Twenty-eight houses and nine chalets, including the historic Wallcliffe House area, have been lost to the fire. Properties have been burnt or damaged at Prevelly, Gnarabup and Redgate," the government said in a fire warning.

The full extent of damage from the blaze, which was sparked by embers from a controlled burn-off in Leeuwin-Naturaliste National Park some 280 kilometres (170 miles) south of Perth, is not yet known.

But the two-storey stone Wallcliffe House, built close to Prevelly Beach in 1865, was burnt through. No lives have been lost.

"The fire threat remains and may worsen at any time and people in this area still need to have their bushfire survival plan in action," the Department of Environment and Conservation said in its warning.

Fire incident controller Roger Armstrong said firefighters were downcast they had lost some homes, as he praised their work in saving other residences in terrible conditions.

"We threw everything we had into Prevelly and we fought pretty hard," he told journalists.

Friday's milder conditions had helped firefighters strengthen boundaries around the fire and there were no homes presently at risk.

"Today's weather is really quite mild, it's in our favour," he said.

"It's not right to say it's under control... so obviously it's not fully contained."

Authorities estimate the blaze has burned about 3,177 hectares (7,850 square miles), forced hundreds of residents and holidaymakers from homes, caravan parks and holiday accommodation and prompted some road closures.

As anger at how a controlled fire could end up destroying people's homes mounted, locals recounted how they were forced to cling beneath a jetty at Prevelly Beach as flames metres-high were burning on the sand.

"All 30 of us huddled underneath the jetty as the fire was raging on the dunes just above us," Joel Hodgson told the ABC.

Firefighter Laurie Drage, who helped adults and children stranded in the water as the blaze raged over the beach said: "It went right over the top of us, like a sheet being thrown over a bed."

"It was like a herd of bulls. It jumped the carpark, it was just amazingly wicked, it was like flying into hell," he told Australian news agency AAP.

Western Australia's environment minister Bill Marmion apologised to those who had lost their homes as he toured the area Friday, saying it was unfortunate an operation to burn off combustible material sparked the blaze.

"I'm happy to apologise for what went wrong," Marmion said.

"My heart goes out to those people who lost a house. If I lost a house I'd feel very emotionally upset and indeed I might have anger against the minister and anyone who might have lighted the fire."

Police Commissioner and State Emergency Coordinator Karl O'Callaghan said the fire was a bad start to the southern hemisphere summer.

"The catastrophic fire conditions that we have seen... it's been a difficult start to the season," he told reporters.