A Code Red fire danger day has been declared in Victoria for the first time in almost a decade, as emergency services warn people in parts of the state's north to consider evacuating their homes.
The Code Red has been declared for Thursday in the Mallee and Northern Country regions.
The last time a Code Red Day was declared in Victoria was over two days in January 2010.
Code Red represents a threat worse than "extreme" and is the highest possible rating on the state's fire danger scale. It is the equivalent to the "catastrophic" fire rating in other states.
There is also a total statewide fire ban on Thursday, to prevent fires spreading to those high risk Code Red districts.
CFA chief officer Steve Warrington warned people in the named districts — which include the cities of Swan Hill, Bendigo and Shepparton — to prepare for the worst.
People on rural properties with high fire risks should travel to safer areas, such as regional city centres, on Thursday, he said.
"What are you going to do tomorrow if there is a fire," Mr Warrington said.
"We are saying, 'do not be there, do not be there when a fire occurs, because you will not survive if you are there'.
"There is a good chance if a fire occurs that your home will be destroyed."
Authorities said even those whose bushfire plan was to stay and defend properties in high-fire risk areas should plan to leave by early Thursday morning.
'Get out tonight or early tomorrow'
Some schools and early learning centres in the affected regions will be closed on Thursday.
Buses will replace some trains.
Emergency Management Commissioner Andrew Crisp said Thursday's conditions would "potentially be the worst conditions [Victoria] will confront in some time".
"If we see fires in those areas, those fires will be fast moving — they will be unpredictable, they will be uncontrollable," he said.
"Houses in those areas, if there is fire, are not built to withstand those conditions.
"The clear message is, if you do not need to be in your home, get out tonight or early tomorrow.
"Your plans need to suit your circumstances, however going to your nearest regional city centre, going to the movies, the pool, or a shopping centre are some options people can consider."
Dozens of schools and childcare centres to shut
Koorlong Primary School, about 15 kilometres from the Mildura CBD, is among almost 50 schools in north-west Victoria closing for the day, with dozens of early childhood services and preschools to also remain shut.
School principal Stuart Pain said the Department of Education told him about the closure just after most students had already gone home.
He said while notifying parents at such short notice was a challenge, families had already been prepared for the fire risk.
Photo: Parents were being notified on Wednesday afternoon about school closures across the state's north-west. (ABC News: Christopher Testa)
"The kids are well in-tune with what's going on with the weather," he said.
"I send home information in the newsletter at the start of the summer season, which was a couple of weeks ago, explaining that we could be shut if one of these Code Red days happened, so we're all well informed.
"The biggest worry the kids had when I told a few of them … was that there was a planned sleepover and activity day on Thursday."
The Code Red declaration will disrupt some other services in Mildura, including kerbside waste collection, which has been postponed until Saturday with the region's landfills and transfer stations all closed to reduce fire risk.
Extreme heat should be short-lived
Most parts of Victoria reached the mid-to-high 30s on Wednesday, and the Bureau of Meteorology's Michael Efron said the evening would be a swelter.
"It's going to be an oppressive night across the state with minimum temperatures generally in the mid-20s across Victoria," Mr Efron said.
He said the "hot and windy conditions" seen across South Australia on Wednesday would extend into Victoria overnight and on Thursday.
Wind gusts above 90 kilometres per hour could reach western and central Victoria on Thursday.
Code Red conditions should develop in the Mallee and Northern Country districts by mid-morning on Thursday.
Melbourne is forecast to reach 39 degrees.
Yet Mr Efron said the heat event would be a short one, with a "squally change" in the mid-afternoon.
"There will be a dramatic drop in temperature of 15 to 20 degrees in an hour."