UPDATE: EMERGENCY services have responded to a number of fires today, including a grassfire which is still going near Maryborough.
The Country Fire Authority issued a "watch and act'' warning for a fire on Camerons Lane at Carisbrook.
A spokesman said it was a fast-moving grassfire and was travelling in a southerly direction towards Moolort.
The fire covers about 100ha.
The spokesman said firefighters have now controlled a fire which started at 1.45pm at Lillicur, about 8km west of Talbot. The bushfire burnt 20ha of grass and bush.
The spokesman said 10 CFA tankers, six "slip-ons'', a bulldozer, two helicopters and 60 firefighters were involved in controlling the blaze which took just over an hour.
Firefighters were also involved in a 12ha grassfire at south-east of Edenhope; a grassfire north of Avenel which affected traffic on the Hume Freeway; a 4ha fire at Murtoa and; a plantation fire at Dartmoor.
Up to nine CFA trucks were responding to a grass blaze in Locksley, 30km north of Seymour, which was spreading south near the Hume Freeway.
Firefighters have also contained fires in Picola, in the state’s north, and Kangaroo Flat, near Bendigo.
A total fire ban had been issued today for the Mallee and Wimmera after temperatures created records.
Mildura recorded a high of 45.4C at 3.18pm, taking it past the record of 45C set in the city in November 1905.
It is now officially the hottest spring day in Victorian history.
The unseasonal late spring weather was due to the arrival of northerly winds which have coincided with the build up of hot weather in the inland.
Mallee schools and nursing homes have been applying extreme heat policies for today's scorcher.
Some parents of young students have been able to pick up their children and other students offered "modified classes''.
Tonight's Mildura harness race meeting will start at 7.30pm rather than 6.30pm to try and miss the worst of the heat.
Temperatures in Hopetoun were almost as high, with the mercury reaching 45C by the middle of the afternoon.
In Melbourne, it reached 38.9C at 3.32pm.
Bureau of Meteorology senior forecaster Dean Stewart said a hot and sticky night was expected, with temperatures remaining in the 30s until the early hours of tomorrow.
Victorians have been warned to take care in the heat and stay well hydrated.
Ambulance Victoria said it had received 10 calls from people suffering from the heat by early this afternoon.
Hundreds of Victorians were sweltering through power outages while the mercury continued to rocket.
Powercor spokesman Drew Douglas said 500 homes near Ballarat, and 100 near Sunshine had been affected by outages, while 300 residents in Windsor and St Kilda East were also stuck without power.
He said Powercor technical crews were on standby in the state's north-west to repair any faults in the network.
Victoria's power usage has soared to 9000 megawatts and was expected to peak about 5pm.
CFA Barwon Southwest Regional Controller Alistair Drayton said "dry lightning" was forecast to hit the region later in the afternoon with storms already rolling through South Australia.
"There is an expectation at around 18.00 today a lightning band will be coming through. That was the cause of the Casterton fires last week, they were ignited by lightning," he said.
"It's a risk for sure and that's something we need to mitigate. When we have dry lightning, which unfortunately doesn't come through with a lot of rain – that's an even that does regularly occur in the southwest area," Mr Drayton said.
He said a variety of aircraft were stationed at control centres in Colac, Hamilton and Stawell and fixed wing aircraft were doing regular "milk runs" to spot potential dangers throughout the state.
"They fly over troubled areas in relation to potential risks. If there are smoke sightings they give us intelligence from the sky," he said.
The CFA warned farmers to be vigilant as the mix of high temperatures and relatively low humidity meant that once a fire starts it could develop quickly.
Workers will be told to down their tools in the heat, with union CFMEU stating they will stop work and leave their site when the temperature hits 35C.
A hot and sticky night is also expected.
Mr Stewart said a forecast change would not arrive until the early hours of tomorrow, so the temperature would remain in the 30s until then.
"It will only be a relatively weak change in that it's going to increase the humidity," he said.
"The temperature will fall to about 23C in the morning following the change."
Additional reporting: Herald Sun.