Hot northerly winds to send south-east Australia into sharp spring warm-up

Temperatures across south-east Australia are forecast to rise as much as 12 degrees Celsius above average after a week of polar air, ABC News reports. The warmth will be brief before another cold front arrives, while seasonal outlooks point to an unusually hot spring and summer.

South-east Australia is set for a rapid transition from winter-like conditions to an early spring heat surge, with temperatures forecast to reach as much as 12 degrees Celsius above average this weekend. ABC News reported that the change will be driven by north-westerly winds carrying hot air from north-west Australia, after a polar blast brought freezing conditions and snow close to sea level in Tasmania.

The cold spell pushed temperatures as much as 10 degrees below average in parts of the south-east. Goulburn fell to minus 7 degrees Celsius, narrowly missing a monthly record. The cold southerlies are now being replaced by warmer air that moved across Western Australia before reaching South Australia and the eastern states.

Sydney is forecast to reach 28C in the city on Saturday and Sunday, with western suburbs expected to reach between 30C and 34C. Much of the south-east inland is also expected to reach the low-to-mid 30s. Mildura and Griffith may record their highest September temperatures in years, while Melbourne is forecast to experience its warmest September day in three years.

The warmth is expected to be short-lived. ABC News said another polar air mass will push temperatures down by 10C to 15C within 24 hours, reaching Adelaide around Sunday, Melbourne and Hobart on Sunday evening, and Canberra and Sydney on Monday. Further warmth is then expected to build during the following week, with temperatures potentially returning to around 30C across the south-east late in the month.

The sharp swings are characteristic of spring, when the temperature difference between tropical Australia and the Southern Ocean is particularly pronounced. Northern Australia is already entering its hot season, while the Southern Ocean remains cold, allowing hot continental air to move south before polar systems quickly reverse conditions.

Seasonal forecasts cited by ABC News indicate that October and November are likely to remain warmer than normal, potentially pushing the spring average above the hot springs of 2024 and 2020. Global models also suggest summer mean temperatures could be 1C to 2C above the 1993-2016 baseline, placing the record-hot 2018-19 summer under threat when compared with previous seasons.