Temperatures are expected to reach the high 30s across northern Victoria on Thursday as forecasters predict it could be one of the hottest October days in more than a decade for some parts of the state.
The CFA has declared a day of total fire ban for the Mallee as temperatures are forecast to reach 38 degrees in Mildura.
Bureau of Meteorology extreme weather forecaster Sarah Scully said hot and windy conditions would likely persist throughout Thursday and peak overnight into the early hours of Friday morning.
"We've got very hot and windy conditions developing across South Australia, New South Wales and Victoria with the potential to reach record-breaking temperatures throughout the day," she said.
"It's going to be a very hot Thursday for Victoria, we're forecasting a maximum of 32 degrees for Melbourne.
"Temperatures are much warmer across northern Victoria, we're forecasting as high as 38 to 39 for parts of the north-west."
Fire danger ratings for the south-west of Victoria have been declared very high, while eastern Victoria and and the northern country have been rated high.
"Those really hot northerly winds are peaking overnight Thursday into Friday morning and that's going to keep the temperatures up so it may make it an uncomfortable night for many Melburnians to sleep in," Ms Scully said.
"We're forecasting a maximum of 38 degrees on Thursday for Mildura but once that cold front moves through, by Friday we're forecasting a maximum of 24 so that's a massive drop in in the daytime temperature.
"It's expected to be the hottest October day in 10 years across many towns in northern Victoria."
Ms Scully said it could be the hottest October day for Mildura in four years.
"[People] will wake up to a warm morning, however, the cold front at this stage is timed to move through around 8am [Friday] so past 8am we're expecting the temperature to quickly plummet," she said.
On a total fire ban day, no fire can be lit in the open air or be allowed to remain alight from 12.01am to 11.59pm.
Strict rules also apply to the operation of farm machinery, chainsaws and lawn mowers.
Total fire ban rules and a map of total fire ban areas are at cfa.vic.gov.au.