With winter drawing closer by the day, just how cold can, and will it get in Australia this year?

Earth's seasons are caused by changes in the tilt of our planet relative to the sun throughout the year. During our autumn, the south pole is edging further away from the sun and if you were to look up at the sun from Australia (which isn't recommended), it would appear a little bit lower in the sky each day.

The sun reaches its lowest point in our sky at the winter solstice, which usually occurs on June 20th or 21st each year. It's no surprise then that Australia’s lowest temperatures on record have occurred in late June.

The lowest temperature on record in Australia was minus 23 degrees Celsius at Charlotte Pass in NSW on June 29th, 1994.

The next coldest places in Australia is Perisher Valley in NSW, which dropped to minus 18 degrees, also on June 29th, 1994.

Last year, the lowest temperature in Australia was minus 12.1 degrees at Perisher Valley and in 2016 it was minus 10.4 degrees at Thredbo AWS.

So, how cold is it likely to get this winter?

It's not possible to predict the value of the lowest temperature for the season ahead. This is simply because computer models aren’t able to reliably forecast minimum temperatures for individual locations more than a week or two ahead.

However, we can take a look at the overall trend that's expected across southern Australia this winter, which is where the season's lowest temperatures are likely to occur.

According to the Bureau of Meteorology, minimum temperatures are likely to be above average across southern Australia this winter.

This forecast is partially due to the weather systems that are expected to affect southern Australia over the next three months, and partially a reflection of our planet’s warming climate.

A background rise in global temperatures is making cold weather observations at the extreme end of the scale less likely across most of Australia.

According to an analysis by the Bureau of Meteorology, the average number of nights with a temperature below zero degrees has dropped across most of NSW, Victoria and Tasmania during the last several decades. Most of the locations analysed in these three states now experience between two and five fewer nights below zero in a decade than they did around the 1970's.

Almost every location analysed across southern Australia is also seeing fewer nights where the minimum temperature falls within the bottom ten per cent of historical observations.

Eight of the 10 lowest temperatures recorded in Australia occurred before 1995. While it's not impossible for Australia to break its minimum temperature record of minus 23 degrees celsius during 2018, it doesn't seem probable.

However, we will just have to wait and see. It only takes one strong cold snap, after all.