Victorian authorities have told thousands of visitors and residents in East Gippsland – an area half the size of Belgium – to leave immediately as a bushfire threat looms.

The emergency management commissioner, Andrew Crisp, issued the order on Sunday ahead of what the Bureau of Meteorology has called one of the “significant fire weather days in Victoria’s history”.

The final two days of the Falls Festival in Lorne, south-west of Melbourne, were cancelled on Sunday morning in anticipation of the extreme fire risk.

The Otways in south-west Victoria, where the festival is held, and the alpine region including east Gippsland, are forecast to experience extreme heat and damaging winds, and thunderstorms are expected to bring dry lightning and new bushfires on Monday night.

There were three active fires in east Gippsland on Sunday with a combined area of more than 130,000ha. An evacuation warning has been issued for the east Gippsland town of Goonergah, which is surrounded by high-value old growth forests.

East Gippsland is popular with campers and holidaymakers over the New Year period. Up to 30,000 people ar on holiday at Lakes Entrance, 300km east of Melbourne.

The main road in and out, the Princes Highway, was likely to be affected by fires on Monday, Crisp said. The Great Alpine Road, the other road out of East Gippsland, is already closed due to bushfires.

“What we are saying now, based on the conditions that will be confronting us tomorrow across the state, but in particular in east Gippsland, is that if you’re holidaying in that part of the state, it’s time that you left,” he said.

“We want to give people time to leave east Gippsland now. So if you’re camping, if you’re in a holiday home, it is time … to leave this afternoon.”

Emergency Victoria outlined a potential impact zone beginning just east of Bairnsdale and extending south along the coast to Cann River and then north to the NSW border. North of Bairnsdale, the impact zone stretches up to Omeo and then cuts back to the Deddick Valley.

The total affected area is about 15,000 square kilometres.

People who live in east Gippsland have been advised to stay with family or friends in Bairnsdale or other larger towns, and to leave no later than Monday morning.

Crisp said Parks Victoria was considering closing national parks in the region and warned that camping in a national park was “the last place you should be”.

“We are giving you fair warning: you should not be in the parks,” he said. “You might think you know where the fires are. There could be fires that start and they could be close to you. You might not find a way out of where you are at the moment.”

The Guardian