Tens of thousands of residents and holidaygoers in the Australian state of Victoria have been urged to evacuate “immediately to survive”, as escalating bushfires threaten an area the size of Montenegro.

The popular summer holiday destination of east Gippsland is experiencing temperatures north of 40C, with strong winds expected to fan already out-of-control blazes and dry lightning forecasted to spark new fires.

Emergencies chief Andrew Crisp told those in the region to leave no later than Monday morning to avoid what authorities warned would be one of the most significant fire weather days in Victoria’s history.

But the Australian Broadcasting Corporation reports that some residents appear dismissive of the fire risk, claiming “it will be fine”, while others are choosing to stay put lest they put additional pressure one of the few remaining thoroughfares out of the region – the Princes Highway.

With other highways already shut due to bushfires, authorities urged people to heed the evacuation warnings early, suggesting a panicked last minute exit – and wildfires – could block the road. It has now reopened after being partly closed for several hours late on Sunday.

States of emergency declared as bushfires rage across Australia Show all 15 1 /15 States of emergency declared as bushfires rage across Australia States of emergency declared as bushfires rage across Australia A firefighter works on a bushfire believed to have been sparked by a lightning strike that has ravaged an area of over 2,000 hectares in northern New South Wales state AFP via Getty Images States of emergency declared as bushfires rage across Australia A dehydrated and injured Koala receives treatment at the Port Macquarie Koala Hospital AFP via Getty Images States of emergency declared as bushfires rage across Australia A water tanker airplane drops fire retardant on a bushfire in Harrington, New South Wales EPA States of emergency declared as bushfires rage across Australia Firefighters tackle a bushfire to save a home in Taree, 350km north of Sydney AFP via Getty Images States of emergency declared as bushfires rage across Australia A kangaroo is seen by the burnt remains of a vintage car in Torrington Getty Images States of emergency declared as bushfires rage across Australia Photo taken on November 9, 2019 shows bushfires taken from a plane in over north eastern New South Wales AFP via Getty Images States of emergency declared as bushfires rage across Australia Andrew Mackenzie surveys the damage around his home in Torrington Getty Images States of emergency declared as bushfires rage across Australia Fire and Rescue NSW firefighters conduct property protection as a bushfire burns close to homes on Railway Parade in Woodford NSW AP States of emergency declared as bushfires rage across Australia Australian Prime Minister Scott Morrison (L) comforts 85-year-old resident Owen Whalan at an evacauation centre in Taree 350km north of Sydney AFP via Getty Images States of emergency declared as bushfires rage across Australia Fire burns at Bolivia Hill in Glen Innes Getty Images States of emergency declared as bushfires rage across Australia A resident puts out small fires as he rides his motorcycle in Old Bar, New South Wales EPA States of emergency declared as bushfires rage across Australia A fire rages in Bobin, 350km north of Sydney on November 9, 2019, as firefighters try to contain dozens of out-of-control blazes AFP via Getty Images States of emergency declared as bushfires rage across Australia Construction workers speak as smoke haze drifts over Sydney, Australia EPA States of emergency declared as bushfires rage across Australia A vintage Jaguar car sits in ruins after a bushfire destroyed a property in Old Bar, 350km north of Sydney AFP via Getty Images States of emergency declared as bushfires rage across Australia A fire rages in Bobin, 350km north of Sydney AFP via Getty Images

“You should not be there tomorrow and we want you to get out now,” Mr Crisp said. But the Country Fire Authority began to warn on Monday morning that for those in some areas, it was already too late to leave.

The state broadcaster estimates 30,000 people had been holidaying in east Gippsland when the “severe” fire warnings were issued.

There are a further seven “extreme” warnings in place across Victoria, with a warning in each of the vast state’s districts.

Earlier on Sunday, organisers of a music festival in the state, expected to run until New Year’s Eve, cancelled the event due to the fire risk. About 9,000 people were already camping on site.

Mr Crisp warned that while 1000 firefighters, 60 trucks and more than 70 helicopters and planes were on standby, “rest assured there aren’t enough trucks to go around”.

The state of New South Wales (NSW) is also facing severe fire conditions over coming days, with conditions expected to reach their most dangerous on Tuesday.

NSW is one of Australia’s most populous koala habitats, and environment minister Sussan Ley warned up to 9,000 koalas may have been killed in this year’s fires – accounting for roughly one third of their population.

Ecologists also believe 480 million animals could have been killed since the fires started in September, which have burnt more than five million hectares (12 million acres) and killed eight people.

On Sunday, prime minister Scott Morrison, risked controversy as he said world-famous fireworks in Sydney would go ahead, despite more than 250,000 people signing a petition to the contrary, fearing they could spark new fires or risk further traumatising individuals affected by the crisis.

Firefighting authorities, however, have refused to rule out the chance of cancelling the display at the last minute.