Today may be the shortest day of the year across Australia, but those hoping the worst of the winter chill is behind them will be sorely disappointed.

In Australia, the winter solstice marks the date on which the southern hemisphere reaches its furthest tilt away from the sun.

When the southern hemisphere reaches its winter solstice, the sun appears at its lowest point in the sky when viewed from south of the equator.

This phenomenon results in the shortest day of the year based on time between sunrise and sunset.

Because of the differing latitudes of Australia’s capitals, our major cities will having varying hours of daylight, with Hobart having the shortest day and Darwin the longest.

• Sydney 9 hours 54 minutes
• Melbourne 9 hours 32 minutes
• Canberra 9 hours 46 minutes
• Adelaide 9 hours 48 minutes
• Perth 10 hours 3 minutes
• Brisbane 10 hours 24 minutes
• Hobart 9 hours and 1 minute
• Darwin 11 hours and 24 minutes.

More cold to come

While the winter solstice may mark the shortest day, “seasonal lag” means temperatures are still set to drop.

Seasonal lag is when the Earth’s surface, especially its oceans, takes time to lose heat.

The oceans absorb the sun’s warmth during summer and slowly release it in the following months, acting as a thermal blanket. 

Even after the chilly weather so far this year, Australia’s surrounding oceans are still releasing warmth into the air.

When will it get coldest, and where?

In most of our capitals – in southern and coastal Australia – the coldest mornings generally don’t arrive until mid to late July.

Cities such as Sydney, Melbourne, Adelaide, Perth, and Brisbane are heavily influenced by nearby oceans and the changes in temperature they generate.

Those in central Australia, which are further from the coast, won’t experience the same delay and may have their coldest nights any time from now.

People living in our far north may miss the seasonal changes, with the Bureau of Meteorology pointing out that in Australia’s northern tropics there is little difference between average temperatures in winter and summer.

Warm winter

While there are undoubtably colder nights (and mornings) to come for most of Australia, there may be a somewhat unwelcome respite this year.

Last month the BoM’s updated seasonal outlook predicted one of Australia’s warmest winters on record.

BOM modelling in April indicated a winter of unseasonably high temperatures would follow our two warmest winters on record in 2023 and 2024.

Since August 2024, Australia has experienced a mean temperature – the average of minimums and maximums – that is 2.1 degrees above the baseline average from 1961-1990.

This equates to a temperature about 2.5 degrees warmer than pre-industrial levels.

The BOM modelling predicted a mean temperature of about 1.5 degrees above the 1961-1990 baseline across Australia.