Melbourne is shivering through its coldest start to winter in 36 years, with forecasters confirming overnight temperatures have averaged less than five degrees for the first six days of the season.

It was a cool and foggy start for many this morning, with city skyline wrapped in a thick blanket, along with the eastern suburbs.

Early commuters switched on their headlights to navigate through the murky conditions, with all drivers urged to take care on the roads.

The conditions caused a few headaches at Avalon Airport, with two Jetstar flights cancelled and another two delayed by up to an hour and a half. Passengers impacted by the cancelled flights were offered bus transfers to Tullamarine Airport.

But as light winds helped clear the fog, brilliant blue skies and sunshine shone through, warming up early exercisers and rugged up workers heading into the office.

Melbourne is forecast to reach a top of 18 degrees today.

Thankfully the cold conditions aren’t expected to stick around, with most of Australia forecast to be drier and warmer than average throughout winter this year.

"The winter outlook follows one of Australia's warmest autumns on record and its second-warmest summer on record," a BoM statement said.

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