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Sydney hits 42.2°C, its equal hottest December day on record

Source Weatherzone Fri 19 Dec 2025

Sydney is having its hottest day in seven years and its equal hottest December day on record after the mercury soared to 42.2°C. Westerly winds and clear skies have allowed an extremely hot air mass to be driven across the Sydney Basin today, Friday December 19, 2025. This heat was exacerbated by two things: The Foehn effect – where the air heated as it descended the eastern slopes of the Blue Mountains. The Urban heat island effect – additional heating caused by man-made materials across the Sydney Basin, including roads, airports, tiled roofs and concrete buildings. The heat arrived early in the day, with the city’s main weather station at Observatory Hill already reaching 34°C by 10am. Then at 1:35pm, the mercury hit 42.2°C. Image: Sydney’s minimum and maximum temperatures over the last 5 days, showing a warming trend culminating in Friday’s 42.2°C. Source: Weatherzone. Friday’s maximum of 42.2°C was Sydney’s hottest day since January 7, 2018. It was also the equal hottest December day in records dating back to 1859, matching the same reading on December 20, 1957. Friday was also Canberra’s hottest day in five years, with the city reaching 39.4°C. - Weatherzone © Weatherzone 2025