The city is on track to pass an entire summer without cracking 40 degrees, despite early predictions of a particularly hot and dry season.

Bureau of Meteorology senior forecaster Rod Dixon said Melbourne has experienced unusually cool weather, with multiple days where the mercury has stalled at 17 degrees.

But repeated spells of scorching weather have nonetheless led to a slightly hotter-than-average summer.

"What's been remarkable about this summer is the number of cools days around the 20-degree mark," Mr Dixon said.

"We've had fairly persistent ridges of high pressure to the south and west of the state that have brought mild southerly winds to most of Victoria, which has pushed the heat to northern Victoria, New South Wales and Queensland.

"Because Melbourne is closer to the coast, we've had milder conditions than in the northern part of the state.

"We've had numerous days around 35-37 degrees, and that's what's bumped up the average."

The average temperature for December was 25.5 degrees, one degree above average.

The January average was 26.5 degrees, again only just slightly above average by half a degree.

December 28 was our hottest summer day, with a maximum temperature of 38.2 degrees, followed by a high of 37.8 degrees on January 17.

Meanwhile, Sydney is heading for its hottest ever January for overnight temperatures.

In Melbourne, with just a few days left of summer, it is unlikely the city will record a temperature in the 40s.

The forecast for Monday and Tuesday is for sunny days in the low 30s.

Mr Dixon said while Melburnians have become accustomed to a few scorching summer days in the 40s, the weather pattern the city has experienced this season wasn't "too unusual".

"The last summer where we didn't have a 40-degree day was 2014-15," he said.

"But we tend to average at least one day above 40 each year."

The weather bureau's outlook for autumn signals below-average rainfall over the southern two-thirds of Australia.

March is likely to be hotter and drier than average across most of Australia, with warm days and nights, except for the far north and west of the country.

The drier-than-average outlook is likely to occur as a result of higher-than-normal pressure systems across western and southern Australia, meaning less rain on the coast.

In Victoria, Mr Dixon said maximum and minimum temperatures would likely be above the historical average for the season, while rainfall was forecast to be below average.