Residents of more than 1,000 homes in Victoria have been urged to leave before sunset in anticipation of a massive fire spreading and the onset of a severe heatwave.

Six fires were burning across the state on Monday afternoon, and authorities were concerned that Tuesday’s heatwave conditions and forecast northerly winds could cause the fire in the Otways to spread as far as Lorne.

Gellibrand resident Rob Murphy was helping out at the Gellibrand River Hotel Pub while his farm was under threat.

“The fire is very close to our property, and depending on the winds, will likely impact our farm,” he told Guardian Australia.

“At the moment, the house is probably OK, but who knows what tomorrow brings.”

Those living in the south-western Victorian towns of Gellibrand, Kawarren, Beech Forest, Forrest, Barongarook, and surrounding areas in the Otways national park were being urged to evacuate after the fire breached containment lines on Saturday afternoon.

Murphy said some people in town were preparing to stay and defend, but many had already left. He said the town had been covered in a thick blanket of smoke overnight, as the fire got within 1km of the pub.

“At the pub now we’re just helping people, making sure everyone’s got a cool drink, making sure people know where to go, and making sure the locals are connected.”

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The Otways fire had burned approximately 9,400 hectares and could spread as far as Lorne, State Control Centre spokesperson Reegan Key said on Monday.

“We’ve had six aircraft working on it, more than 300 firefighters, but with very strong winds and very warm temperatures coming again tomorrow, we have extreme fire danger in that area of the south-west,” Key said.

“We’re really concerned about the potential of that fire to take a big run and impact communities into upper Gellibrand, Forrest, Barongarook, and potentially, if it’s very bad, even as far as Lorne or Aireys Inlet tomorrow.”

Victoria police and State Emergency Service crews began doorknocking homes and properties in the Greater Otways area on Monday, strongly recommending that residents evacuate immediately.

“We’re asking them to evacuate before sunset today, because … we just don’t want them in those areas tomorrow with such terrible conditions,” Key said.

A statewide total fire ban has been issued for Tuesday, and all visitor sites in the Great Otway national park and State Forests have been closed until further notice with severe heat forecast.

Fire conditions are forecast to be extreme in five districts across the state – Central, Mallee, North Central, South West and the Wimmera – with the fire danger rating in the Wimmera only a few points of catastrophic conditions.

Key said the state had not experienced heat of this intensity since 2009, with the Bureau of Meteorology forecasting temperatures in Ouyen and Mildura in north-west Victoria would reach 49C on Tuesday.

The hot weather, combined with a “significant” wind change due to hit later on Tuesday afternoon, would make battling blazes difficult, Key said.

“Those are always conditions in Victoria that cause trouble with firefighting,” she said.

There were six active major fires across the state on Monday, with three of concern; the Otways fire, the Walwa fire, and one in the Alpine national park, heading down towards Dargo.

Residents near the Murray River were also told to leave their homes as firefighters battled a blaze that had spread through a wilderness park.

The order issued on Monday covered Nariel Valley in northeast Victoria and includes McNamara Crossing, Staceys Bridge, and surrounds.

Several locations in Victoria’s north were facing the prospect of seven consecutive days of maximums above 40C.

– with AAP