'Life is irreplaceable': Stark warning to thousands as two bushfires merge

Two out-of-control bushfires have merged in Victoria's East Gippsland where emergency alerts have been issued and an evacuation order remains in place.

The bushfires near Ensay and Tambo Crossing have joined at the southern end and remain very active with extreme fire behaviour, authorities warn.

An emergency warning has been issued for Brookville, Dogtown, Double Bridges, Ensay, Holstons, Nunniong, Reedy Flat, Stirling, Tambo Crossing, Timbarra, Wattle Circle.

East Gippsland Mayor John White had a stark warning for all residents and tourists in the fire-affected areas.

An aerial image of the fires at Cabbage Tree Creek on Sunday.Source: DELWP Gippsland

“Hopefully people heed the messages. You can rebuild homes, sheds and fences but life is irreplaceable,” he told The Herald Sun.

Swifts Creek shop worker Richard Darby said “silly” people were refusing to leave.

“It’s going to be a very bad day tomorrow, they are telling everyone to get out while they can,” he told the publication.

“There are 100km/h winds tomorrow, that could be suicide. We are expecting lightning tonight.”

Another emergency warning has also been issued further east at the Wingan River fire, which has burnt through more than 27,000 hectares.

The Princes Highway has been closed between Cann River and Genoa because of the fire threat, so is Great Alpine Road between Bruthen and Ensay.

That section of Great Alpine Road is expected to be closed for up to 14 days.

An evacuation order issued on Sunday, telling about 30,000 tourists at Lakes Entrance and thousands of residents in the area to leave, remains in place.

"At this point in time you need to get out of there," Emergency Management Victoria Commissioner Andrew Crisp told Nine on Monday.

"If you are not out by 9am you need to stay across the conditions.

"We have seen new fires as a result of thunderstorms and dry lightning and we have seen significant new fire in the east of the state near the Cann River."

A fire burning in East Gippsland shire region. Source: DELWP Gippsland

Temperatures are set to soar into the 40s across Victoria on Monday, with a total fire ban in place across the state and extreme fire danger ratings in most regions.

Melbourne could face its third day above 40 in December – an occurrence not seen since 1897.

The Bureau of Meteorology expects strong and gusty winds throughout Monday, as well as thunderstorms that will give way to much cooler air across Victoria later during the day.

More than 70 helicopters and planes will be working on Monday if conditions allow.

The forecast conditions, including winds up to 100km/h, forced organisers of the Falls Festival on Victoria's west coast to cancel the event, with 9000 festival-goers told to pack up and leave.

The transport department urged Melbourne residents to consider their travel plans on Monday, as temperatures in the city are expected to reach 43C in some suburbs.

Heat and winds to wreak havoc for NSW firies

Dangerous fire weather and poor air quality are forecast for NSW as firefighters brace for deteriorating bushfire conditions ahead of New Year's Eve.

The Bureau of Meteorology says temperatures will start building on Monday and are likely to climb past 40C in western Sydney and parts of regional NSW by Tuesday.

"Conditions will deteriorate again as it heats up on Monday with very high to severe fire dangers forecast for areas of the state," the bureau said on Sunday evening.

The NSW environment department is forecasting poor air quality in Sydney on Monday, warning that pollution will be "unhealthy for sensitive people", particularly those with heart or lung diseases.

RFS commissioner Shane Fitzsimmons says deteriorating weather conditions could result in "extreme" fire danger across large parts of the state by Tuesday.

"We can expect a broad geographic area of extreme fire danger ratings, which will extend through places like the southern ranges, the Illawarra south coast and probably down through to the Monaro area, down through the high country," he told reporters on Sunday.

Severe fire danger ratings are in place on Monday for the southern Riverina, southern slopes, Monaro alpine region, southern ranges and far south coast.

NSW Rural Fire Service crews fight the Gospers Mountain Fire as it impacts a structure at Bilpin last week. Source: AAP

Total fire bans are also in place for large chunks of eastern and southern NSW.

"Deteriorating conditions are forecast the next few days with expected high temperatures and strong winds," the RFS said on Sunday evening.

"If you have plans to travel through or are staying in bushfire prone areas during this time you should consider the risk, monitor changing conditions and be aware that roads may be closed without warning."

The NSW Rural Fire Service says Sydney's New Year's Eve fireworks display is unlikely to be canned despite concerns about bushfire conditions.

South Australia fires fuelled by 40C heat

Catastrophic bushfire conditions in three South Australian districts will have firefighters on alert as the state swelters amid high heat and rising winds.

The temperature is forecast to reach 40C in Adelaide on Monday, with some regional centres to get even hotter.

But it's a cool change in the afternoon that is causing the most concern, with strong and shifting winds set to heighten the risk of bushfires spreading.

The Country Fire Service is particularly worried about the potential for breakouts from the Adelaide Hills fire, and from a blaze on Kangaroo Island that continues to smoulder.

The Adelaide Hills fire has already burnt through 25,000 hectares and destroyed more than 80 homes since it was sparked amid similar conditions 10 days ago.

CFS chief officer Mark Jones said it was regrettable that the same conditions had returned so soon.

"The potential for hot-spot breakouts tomorrow is incredible across the whole fire zone," he said.

The catastrophic conditions will stretch across the Adelaide Hills, through the mid-north and across to Yorke Peninsula.

Other areas of the state will have either extreme or severe warnings in place.

Tasmania also facing extreme heat

Tasmanians have been urged to remain alert to fire risks as the state faces 40C temperatures in southern and eastern areas.

Hobart is forecast to reach 40C and Launceston is expecting a maximum temperature of 34C on Monday, with thunderstorms and wind gusts of 80 to 90km/h also forecast.

The forecast combination of heat, thunderstorms and wind gusts have triggered extreme and severe fire dangers warnings across the state.

"A total fire ban has been declared across the state and is set to continue until Tuesday morning," Emergency Management Minister Mark Shelton said.

"People are being urged to remain vigilant. It is vital that people know what to do if a fire threatens their home or property."

Tasmanians were also encouraged to have a plan to keep in touch with older or sick relatives, friends and neighbours.

Tasmania Fire Services recommended people living in bushland areas to relocate to urban areas for Monday, and campers to reconsider their plans.

"As far as the fire danger goes, tomorrow has the potential to be a very bad day across large parts of the state," TFS chief officer Chris Arnol said.

"Although Tasmania's fire agencies are well prepared, people can't expect to see a fire truck in every driveway and an aircraft above every house."

Do you have a story tip? Email: newsroomau@yahoonews.com.

You can also follow us on FacebookInstagram and Twitter and download the Yahoo News app from the App Store or Google Play.