Australia's Second-Hottest September: Hot Nights, Dry Southeast, Wet West
Australia recorded its second-hottest September on record in September 2026, with mean temperatures 2.71C above the 1961-1990 long-term average. Minimum night-time temperatures were the hottest for any September since country-wide records began in 1910, according to Bureau of Meteorology data reported by The Guardian.
National minimum temperatures averaged 2.52C above average, just above the previous September record of 2.51C set in 2023. The margin was small. The repeat record matters to specialists who track diurnal range, the gap between daytime highs and night-time lows.
Averaged temperatures ranked in the top five warmest Septembers for every Australian state and sixth-hottest for the Northern Territory The Guardian. New South Wales, South Australia and Western Australia each recorded their second-warmest September on record Bureau of Meteorology.
In New South Wales, 45 locations logged their warmest Septembers on record. Mean minimum temperatures for Greater Sydney ranged from 0.3C above average at Mangrove Mountain AWS to 2.8C above average at Sydney Airport AMO. September 2026 was also the fourth-driest September on record for New South Wales and the sixth-driest for Victoria. Both the heat and dryness were centered in the southeast.
Western Australia showed a different pattern. It had its second-wettest September on record, its wettest September since 1904 The Guardian.
Alpine sites recorded high temperatures. Snow depth at Spencers Creek in Kosciuszko National Park fell to zero during September, the first time this happened in any September since records started in 1954. At Thredbo, the average September night-time temperature was 0.1C, the first time the September daily minimum averaged above freezing in 59 years of measurements. Thredbo recorded its hottest September day on record at 16C, about 1C above the previous record set in 2001. Mount Buller, Falls Creek and Mount Hotham all recorded their hottest September maximum temperatures on record.
This September follows a longer pattern. Australia has not had a September with below-average mean temperatures since 2004. Global heating has warmed Australia by more than 1.5C since country-wide records began in 1910. In 2025, the national average minimum temperature was 0.98C above average, the eighth-warmest on record Bureau of Meteorology.
The broader context here is what the combination means for planning. Record-warm nights reduce overnight relief and keep conditions warm heading into the southern fire season. Dryness across New South Wales and Victoria alongside disappearing September snowpack shortens the period between winter recharge and summer demand for water managers, energy operators and alpine resorts. A very wet September in Western Australia does not balance that picture. The pressures remain regional in character, and they point to early, state-specific preparation rather than a single national reading.
