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50°C temperature range in Australia's first week of summer

The opening week of summer featured a massive 50°C temperature range across Australia as freezing weather and snow gave way to intense heat and fires.

The first week of the 2025-26 summer, which started on December 1, saw two contrasting air masses jostling over Australia: cold air originating from the Southern Ocean swept over parts of the county in the first few days of the week before a large pool of hot spread across the continent.

Cold start to the season for the southeast

Summer started off with an unseasonably cold air mass passing over the country’s southeastern states. This wintry start to the season saw snow settling in parts of New South Wales, Victoria and Tasmania as temperatures dropped below -2°C in each state.

Image: Snow at Mt Perisher, NSW on December 1, 2025. Source: Steve Smith

The lowest temperature in Australia during the first week of summer was -4.0°C at Thredbo in the NSW Snowy Mountains on December 2. This was followed by -3.5°C at Liawanee, Tas on December 1 and –2.8°C at Mount Hotham, Vic on December 2.

Canberra also registered its first sub-zero summer temperature on record last week when the mercury dipped to -0.3°C early on December 2.

Extreme heat and fire danger

While people in parts of southeastern Australia were shivering in the opening days of summer, hot air was brewing in the country’s north and west.

Temperatures at Marble Bar in WA’s Pilbara district became progressively warmer during the first five days of the season:

• December 1: 42.6°C
• December 2: 42.6°C
• December 3: 43.8°C
• December 4: 44.1°C
• December 5: 45.5°C

By Saturday, December 6, the intense heat had spread across central, southern and eastern Australia. Moomba in SA and Birdsville in Qld both hit 46.0°C on Saturday, while heat spreading across NSW saw temperatures reaching 44.2°C in Tibooburra, 42.1°C in Dubbo and 42.0°C in Gosford. A few places in western Sydney also climbed above 41°C on Saturday.

The hot air that swept across southeastern Australia late last week caused a spike in fire danger ratings and resulted in numerous out-of-control bush and grass fires.

At least 19 homes were destroyed by fires in Tasmania and at least 20 homes were lost to fires in the Central Coast and Mid North Coast regions of NSW.

50°C temperature range

The contrasting weather endured by Australians in the opening week of summer saw a massive 50°C temperature range across the country, from -4.0°C at Thredbo, NSW on December 2 to 46°C at Moomba, SA and Birdsville, Qld on December 6.

The first week of summer 2025-26 shows how variable Australia’s weather can be at this time of year.