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Big dry contributes to record cold SA, Vic mornings

Source Weatherzone Tue 20 May 2025

Parts of South Australia and Victoria have again shivered through their coldest May night on record, after numerous minimum temperature records were also broken on Monday morning. Coldstream, in the Yarra Valley on Melbourne's northeastern outskirts, recorded its coldest May temperature in 30 years of records at the local weather station on Monday morning with a minimum of –5.3°C. It dipped even lower to a new May record of –5.5°C on Tuesday morning. Like yesterday, Coldstream set the low bar for the whole of Victoria, and was again more frigid than anywhere in the high country, where Tuesday morning’s coldest reading was –4.9°C at Mt Hotham. Frosty conditions were experienced across all nine Victorian forecast districts overnight. Kanagulk – a rural locality in the Wimmera district – has only had a weather station since 2004, but Tuesday morning's minimum of –4.1°C was its coldest temperature recorded in any month. The minimum of –3°C in Victoria’s third largest city of Ballarat wasn’t quite a record-breaker for May, but it was by far the coldest night of the year to date, and indeed the only sub-zero night so far in 2025.  South Australia also saw widespread frosts across most of the state’s 13 forecast districts. The state low was –4.7°C at Coonawarra in the Lower South East forecast district near Mt Gambier. That was the lowest May reading in 60 years of records and the lowest in any month for 43 years.  Many of South Australia's outback and coastal minimums were also noteworthy. Tarcoola, in SA's arid North West Pastoral forecast district, endured its chilliest May night by almost one degree in records stretching back to 1903. The minimum at 7:21am on Tuesday was –2.5°C. As for coastal SA, Ceduna’s minimum of 0.3°C was a fair way off the May record of –3.2°C, but it was still a very cold night for a coastal town in May. The same could be said for Whyalla’s minimum of 0.6°C (the May record is –0.4°C). Image: Minimums for Tuesday, May 20, 2025. You can see the location of Tarcoola (mentioned above) near the top left of the image. Why such cold nights in May? As mentioned yesterday, clear skies and dry air in a southerly airstream behind the weekend cold front were the main drivers of the current spell of frosty nights. But there has been another factor at play. Large parts of South Australia and Victoria are currently enduring a prolonged drought, which in some areas is the driest 15-month spell ever experienced in more than a century of records. That bone-dry landscape would have contributed to this week's low minimums because it helped keep the air just above the ground dry, which exacerbated the cooling. Nights will gradually warm by a few degrees throughout the week in most of the areas mentioned, although it will still be cool and dry enough for widespread frosts. - Weatherzone © Weatherzone 2025