Melbourne is expected to swelter through the hottest day since Black Saturday a decade ago, while Mildura braces for its warmest day since records began.

Today will reach 44 degrees ahead of a cool change at approximately 3pm this afternoon, when the temperature is expected to drop by 15 degrees in just 20 minutes.

Conditions are also extremely dry, which heightens the risk of fire. The Country Fire Authority (CFA) has expressed the importance of fire preparation after two extremely hot weeks and dry conditions.

People are urged to double-check their emergency plans given the current situation is reminiscent of some terrible times in the past. 

Victorians are also being reminded to stay hydrated and check on the young and the elderly throughout the day before the sudden drop this afternoon.

Those wanting to avoid the extreme heat should make their way to Portland, which is predicted to be the coolest town in the state at 28 degrees. 

Authorities recommend people use non-essential electronics, such as dishwashers, washing machines and pool pumps during these peak times, to ease the strain on the national grid through the extreme heat.