Parts of Australia on track for warmest start to winter on record amid influx of tropical air

An influx of humid, tropical air has resulted in a remarkably warm and relatively wet start to winter across Australia.

And with abnormally high temperatures forecast to continue, many regions are on track for the warmest start to winter on record.

While the mild weather has set back the snow season, farmers are rejoicing with twin rainbands forecast to soak southern states this week.

Winter temperatures running at mid-autumn levels

Short spells of warm weather are not unusual in early winter, however the current prolonged run of unseasonable heat is heading into its second week and for south-east states, daily temperatures will persist at around 5 degrees Celsius above normal.

Sydney is on track for its warmest start to winter on record, beating all years back to 1859 when the site opened, with maximums averaging comfortably above 20C so far this June, and overnight minimums above 12C.

Hobart is also seeing a record mild start to June with temperatures around 3 degrees above normal, while Melbourne is recording its warmest start to winter in 21 years and Canberra 18 years.

Adelaide has been slightly cooler than the city's exceptionally balmy start to winter in 2023, but is still running at more than 2C above average.

Brisbane and Darwin have also been warmer than normal, while Perth, located well away from the Tasman high, is the only capital which has observed weather matching the season.

When will cold weather return？

So why does it feel like the middle of autumn in the middle of June？

The well above average temperatures are chiefly due to stubborn regions of high pressure in the Tasman Sea.

Winds blow anticlockwise around a high in the Southern Hemisphere, and its position off the east coast is directing northerly winds over Australia while also deflecting cold fronts away to the south.

Adding further to the heat, streams of tropical moisture are being carried south by the northerlies, the ideal set up for cloudy and muggy nights.

The current pattern is unlikely to break down this week, preventing cold weather from returning for at least another seven days.

For our capitals, this week is forecast to bring peak temperatures of:

• 23C in Sydney, 6C above average.
• 20C in Adelaide, 4C above average.
• 19C in Melbourne, 5C above average.
• 17C in Hobart, 5C above average.
•  17C in Canberra, 5C above average.

The high should slowly exit the Tasman Sea to the north of New Zealand next weekend, allowing colder air to arrive from the Southern Ocean.

However, long-range modelling is predicting this winter will be nationally one of the warmest on record.

Wet start to winter to continue under twin rainbands

There's one group of Australians who are rejoicing in the mild and wet start to the month, and that is farmers.

Parts of the Murray-Darling Basin and Western Australia Wheatbelt have already exceeded their June average rain, including some drought affected areas near the Queensland-NSW border.

And there is more rain on the forecast.

A north-west cloudband formed across WA on Thursday and Friday, and fed by copious moisture off the northern Indian Ocean, it dropped rain across nearly the entire state.

Shark Bay was the wettest location, notching up 82 millimetres in 24 hours to 9am Friday — about double the average for the entire month.

The cloudband is now spreading over South Australia, Victoria and Tasmania, and while it will peter out over NSW on Sunday, a second rainband will quickly develop across WA.

This next system will be slow moving and therefore has the potential to bring higher totals. It will soak much of WA during the coming days, then reach SA from Monday.

But the heaviest falls should arrive in SA on Tuesday and Wednesday, followed by eastern states from Thursday.

All up, the twin bands should deliver from 15 to 50mm of rain across a broad belt of southern Australia through the next eight days, while patchier rain spreads north to western Queensland and the Northern Territory.

A wet June was perhaps not on everyone's bingo card, especially considering El Niño has just been declared by the National Oceanic and Atmospheric Administration (NOAA).

But the influence of El Niño does not appear to have arrived on our shores just yet, although modelling favours drier months from July onwards.

Snow season back to zero

There are often winners and losers in weather, and unfortunately the wet and mild conditions have melted most of the alpine snow which fell earlier in the month.

Even snowmaking, often the saviour for Australia's fickle snow season, has been limited thanks to a string of nights above freezing.

And conditions will deteriorate further this week as the northerly winds and tropical moisture results in rain, along with daytime temperatures as high as 10C.

A lack of snow in June is not uncommon, but the alpine community will be hoping the likely colder weather later this month delivers a few dumps of snow, especially since the success of a season often hinges on sufficient coverage arriving by the July school holidays.