"We've had a sea-breeze which has moved in already through the southern suburbs and is pushing its way into the northern suburbs," said Bureau of Meteorology forecaster Andrea Peace.

"The sea-breeze is moving in now and we're expecting things to cool quite considerably. We're certainly not going to reach those really high temperatures we had yesterday."

Melbourne reached a top of 39.9 degrees on Thursday, its warmest December day in three years.

Overnight temperatures only fell to 22 degrees in Melbourne, making for an uncomfortable night's sleep and the heavy use of air-conditioners.

While Melbourne will be cool, much of the state away from the coast will be sweltering.

Even in parts of Gippsland, temperatures will be in the high 30s, with Bairnsdale reaching 39 degrees, Sale 35 and Orbost 41.

The state’s north-west will reach the low-to-mid 40s, with Mildura, Birchip and Ouyen getting to 44 and Swan Hill and Kerang 43.

From Saturday to Wednesday, Melbourne will enjoy mild temperatures in the mid-20s, with Christmas Day tipped to be mostly sunny and 26. Boxing Day will mark a return to high temperatures, with a top of 33 and sunny.

According to the Australian Energy Market Operator, Victoria’s peak electricity consumption yesterday on Thursday was around 9000 megawatts, reached at around 5pm.

‘‘This compares to a typical December day with an average maximum temperatures of around 24 degrees and maximum electricity consumption of around 6000 megawatts,’’ said a spokeswoman.