Melbourne is preparing for its warmest November day in four years with the temperature set to hit 38C.
The first total fire ban of the season has been issued for the Mallee region on Monday while thunderstorms - forecast across the whole of Victoria later in the day - could pose a wider fire threat.
The CBD had reached 27C by 8.40am and the metropolitan area should hit the forecast top of 38C about 5pm, Bureau of Meteorology senior forecaster Rob Dickson told AAP.
"If we get the 38C today it will be the warmest day in November since 2012 when it got to 39.6C," he said.
A cool change and thunderstorms are expected to arrive in the city about 8pm.
A total fire ban in the Malle in the state's northwest means no fires can be lit or hot work - such as welding - conducted until midnight.
"We've already recorded some thunderstorms across the Wimmera and the southwest this morning," Mr Dickson said.
"Any storm could spark some fires but we've had a pretty wet October and spring so we're in a better spot than this time last year."
After a sizzling hot Monday, Melbourne should have cool to mild days for the rest of the week, with a top of 19C on Tuesday and 18C on Wednesday.
Kidsafe Victoria general manager Jason Chambers says with the hot weather, parents and carers are reminded never to leave children in hot cars.
"The temperature inside a car can be 20-30C warmer than the outside temperature," he said.
"Based on Monday's forecast, the temperature inside a parked car could easily reach over 50-60C in a matter of minutes."
