A blocking high centred over Tasmania pushed the air pressure to a provisional Australian record on Monday morning and delivered the coldest night of the year across much of the south-east, with five states dropping below zero.
The mean sea-level pressure reached 1044.5 hectopascals at Ouse, in Tasmania's upper Derwent valley, at about 9:50am AEST on Monday. On Bureau of Meteorology data reported by Weatherzone, that is provisionally the highest mean sea-level pressure recorded anywhere in Australia, above the previous mark of 1044.3 hectopascals set at Launceston on 7 June 1967. The figure is provisional and has not yet been formally confirmed by the Bureau.
High pressure means clear skies and light winds, and in winter that means heat escapes overnight with nothing to hold it in. The result was a widespread cold morning. Melbourne fell to 3.2 degrees, its coldest of 2026, and Melbourne Airport reached 0.1. Coldstream, in the Yarra Valley, dropped to minus 2.7.
Tasmania was colder again. Liawenee, on the Central Plateau, recorded minus 8.1 degrees, the lowest reading anywhere in the country so far this July. That is a cold number, not a record one, and older figures from the same station circulating online belong to July 2024, not this event.
The chill reached further than the two southern states. Yunta in South Australia fell to minus 1.7, Perisher Valley in the New South Wales alps to minus 5.6, and Mount Ginini in the ACT to minus 2.6. Frost warnings were issued for parts of Victoria during the cold spell, and sheep and cattle producers across parts of Victoria and New South Wales were warned earlier in the week about cold-stress conditions for stock.
The high is now moving on. The Bureau's forecast has a change crossing the south-east later in the week, which would bring cloud, rain and mountain snow and end the run of clear, frozen nights. Anyone relying on the cold and still conditions, from alpine operators to growers watching for frost, should check the Bureau's latest forecast and any local warnings before the change arrives.
