Victoria's Christmas weather will go up and down as quickly as Santa shimmies through a chimney.
The state will swelter through a warm and sunny Christmas Day, with Melbourne set to hit 35C and temperatures of up to 39C expected in the northwest before a cool change later on.
A late change in the west will also likely bring some showers and thunderstorms.
And cricket fans may like to pack a brolly for the first day of the Test as Boxing Day ushers in one of the state's wettest days in three months.
Most of Victoria will get at least 10mm of rain, but central and eastern districts will probably be doused with about 20 to 40mm.
The bulk of Melbourne's rain will wash through before 10am, but there will probably be some showers in the afternoon as well, Bureau of Meteorology senior forecaster Richard Carlyon says.
Temperatures are expected to drop to about 20C.
The contrasting weather has prompted authorities to issue warnings about both fire and flooding over the next couple of days.
Some regions have already been assigned severe fire danger ratings, as northerly winds pick up significantly.
The State Emergency Service says festive season campers should be careful around waterways, particularly in central and eastern parts of Victoria.
"Many caravan and camping areas are located on low-lying land close to a river, stream, estuary or beach front," a statement said on Thursday.
"This increases the chance of flooding."
Areas that have recently been affected by fire are also more prone to landslips in wet and windy conditions, the SES said.
