The predicted winter warm spell has arrived in southeastern Australia, with 23°C on the cards for Adelaide this Monday, while Melbourne commences a four-day run of 20-degree weather.

August temps of 20°C or higher are far from unknown in Melbourne.

• While the city's average August maximum is just 15°C, the highest August temp ever recorded was 26.5°C in 1982.
• But runs of 20-degree August weather lasting four days or longer are rare, with only six occurrences in the past (the record is five consecutive August days of 20°C or higher).

Melbourne is of course not the only city to be feeling unseasonable heat this week.

Monday's synoptic chart reveals the two main features stories on Monday’s Weatherzone news feed.

• One feature is strong easterly stream bringing heavy rain to parts of the coastline of Queensland and central and northern NSW.
• The other feature is those warm northerly winds circulating anti-clockwise around that strong high pressure system centred over the Tasman Sea, dragging warm air from the interior of the continent southwards.

Adelaide is heading for 23°C today and had already topped 20°C as we published this story on Monday morning local time.

Hobart is heading for 18°C on Monday and 20°C on Tuesday.

Like Melbourne, 20°C in Hobart during August is not unknown, and is several degrees shy of the city's August record of 24.5°C in 1977. But when you start talking about 20-degree August weather in Tasmania, you know you’re in the midst of a very warm spell for winter.

Even Canberra will get very close to the 20-degree mark later this week, with tops of 19°C expected on Thursday and Friday. Its August record was 24°C, also (like Melbourne's) in the very warm winter of 1982.

By the weekend, cooler conditions will return to all of the areas mentioned as a cold front and associated low pressure system make their way east.

The front does not look particularly strong, so this won’t be a major polar outbreak. Nor does enough snow look likely to fall in alpine areas to repair the damage done by this week's warm temps and possible pre-frontal rain.

There are, however, early indications that winter will return with more of a bite towards the end of next week, with cold showery weather and snow in the mountains. So if you don't like chilly weather, enjoy this week's warmth.