Australian Weather

22 Dec 2025, 11:42PM UTC

Perth will be by far the hottest Australian capital city on Christmas Day, with a maximum of 41°C expected as a broad area of heat bakes the west coast and nearby parts of Western Australia’s inland. The mercury should also rise to the low-40s in WA’s fifth-largest city Geraldton (about 400km north of Perth) on Christmas Day for the third consecutive day. The BoM is predicting low to severe heatwave conditions all the way from Broome in the Kimberley region to Albany in the South Coastal forecast district for the three days from this Tuesday, December 23. Image: The BoM’s Predicted heatwave map for WA for the three days starting Tuesday, December 23, 2025. Why so hot in the west? A strong high pressure system centred over waters southwest of Australia is directing hot air from the continent’s interior over WA, as air circulates in an anti-clockwise direction. That’s part of the equation. Image: Synoptic chart for Tuesday, December 23, 2025, showing the position of the high which is causing heatwave conditions in parts of Western Australia. The other factor contributing to heatwave conditions is a heat trough currently positioned over WA's west coast. Also locally known as a west coast trough, this is a low pressure zone that often forms during the warmest period of the year at the boundary between the flow of hot air from the interior and the cooler air over the Indian Ocean. "The current trough's axis is oriented northeast to southwest, which means it's anchored over northwest WA and then pushes offshore," Weatherzone meteorologist Corine Brown explains. "That means that sea breezes are prevented from developing along the coast, allowing heat to keep building throughout the day. "A delayed sea breeze should kick in late on Christmas Day for coastal centres as the trough moves closer to the coast, but they'll have reached scorching temperatures well before then." Image: The approximate position of the heat trough on Christmas Day is where hot winds from the east and cool winds from the west converge in this chart (the direction that wind the is travelling is indicated by the plain ends of the wind barbs). A heat trough usually sticks around for at least a few days and can last for a week or more. This week’s event should dissipate after Christmas Day, with a return to more comfortable conditions in Perth and the entire South West Land Division from Boxing Day onwards for several days. Perth should reach 27°C on Boxing Day after its 41-degree Christmas Day scorcher, with a run of three days with maximums of 29°C in Geraldton from Friday through to Sunday. Image: Hourly graphs for Geraldton, WA, on the Weatherzone app. Perth’s average December maximum is 29.5°C while Geraldton’s is 31.5°C.

22 Dec 2025, 2:17AM UTC

Snow will fall this week from Tuesday, December 23, for at least a couple of days in elevated parts of Tasmania, with a few flakes likely to persist into Christmas Day. That means a White Christmas for our southernmost state in the heart of the Australian summer. Tasmanian summer snowfalls often consist of just a few flakes at the state's highest points, such as the summit of Cradle Mountain (1545m) or Tasmania's highest peak Mt Ossa (1617m). But this week, snow is expected to fall as low as 900m on the Central Plateau and 800m on more southerly areas by Christmas Eve into Christmas Day. So there's a strong chance that the Christmas snowfalls will be experienced not just by bushwalkers in remote, exposed areas, but by residents of towns like Miena (elevation 1052m, population just over 100) on the southern shore of Tasmania’s Great Lake. Even Hobart residents might be lucky enough to catch a flake or two up towards the 1271m summit of Kunanyi/Mt Wellington, assuming the road is open. How unusual is Australian snow at this time of year? Brief snowfalls tend to occur at the highest elevations of Tasmania and the high country of the southeastern mainland at least once each summer. Indeed, Tasmania saw snow a week ago even as bushfires burned in the state’s east, while snow was reported at the mainland ski resorts on December 1.  While the cold fronts that circulate the Southern Ocean tend to slip southwards during the Australian summer, the occasional pool of unstable polar air is always a chance to push northwards at this time of year. That’s what will occur this week, and it’s largely thanks to the jet stream – the swift-moving "river" of air high in the atmosphere which generally blows from west to east.  The jet stream tends to move in waves in what is known a meridional pattern, sharply dipping to the north and south as it moves east. This week, the meridional pattern will allow cold air to be dragged up towards Tasmania and out into the Tasman Sea. Image: The expected pattern of the jet stream over Australia at 11pm this Wednesday, December 24, 2025, showing air from the south being pushed over Tasmania. While the far southeastern mainland will be relatively cool for much of this week, the coldest air and most of the associated moisture will stay south the mainland. Melbourne will experience a brief touch of wintry weather on Christmas Day, with an unseasonably cool maximum of just 17°C. When Melbourne gets cold in winter, Canberra generally does too. But the national capital will miss the coldest weather this week, with a sunny maximum of 26°C expected on Christmas Day – although there will be a chill on Boxing Day morning after a minimum of just 6°C.  In Hobart, a showery Christmas Day should reach just 16°C, with Boxing Day topping out at a brisk 15°C even though skies will start to clear.