Sydney has officially recorded its hottest June since records began in 1859, with the Bureau of Meteorology confirming a mean temperature of 16.1°C, surpassing the previous record of 15.7°C set in 1991. The month saw 15 consecutive days with maximum temperatures of at least 20°C between 7 and 21 June, breaking the previous June record of nine consecutive days set in 1919.
Record-breaking temperatures and ocean heat
According to a Bureau of Meteorology spokesperson, the average maximum temperature (20°C) and average minimum (12.2°C) each ranked as the second-highest on record individually, but their sustained consistency secured the overall warmest June. Experts attribute the warmth to record-breaking ocean temperatures off the NSW coast.
Professor Matthew England, an oceanographer at UNSW and director of the ARC Centre of Excellence for Our Future Oceans, described the ocean as a global "warming hotspot" experiencing rapid temperature increases. "The basic balance in our climate system is that the oceans absorb a lot of heat during summer and they radiate that heat back into the atmosphere during winter," he said. "Those very warm oceans off Sydney would be a significant contributor to the record warmth we've had this winter."
Climate scientist warns of global warming signature
Professor Andy Pitman, a Sydney-based climate scientist, expressed a "complete lack of surprise" at the new record. "It's got the signature of global warming all over it," Pitman said. "With temperature, there's no wriggle room around it any more … We know that the warming is due to the failure of governments around the world to deeply cut emissions."
Pitman noted that vegetation that should be dormant during winter was "happily transpiring", drawing moisture out of the soil and amplifying heating due to CO2. He warned that unless decent rain arrives, this could lead to dry springs and elevated fire risk.
False sense of security and future risks
While a milder winter might feel pleasant, England warned that "the actual cost of high-end events is severe" and that "people can kind of be lulled into a false sense of security." Looming heatwaves and bushfire risks will be heavily amplified by El Niño shifting moist air away from eastern Australia.
Pitman urged immediate action, noting that a recent NSW Net Zero Commission report highlighted severe gaps in climate adaptation. "The climate science community have been warning about this since at least 1995," he said. "Serious contingency planning needs to be in place for extreme heat. I don't think Australia is prepared for the kind of heat it's likely to experience."
Widespread heat across eastern Australia
The unseasonal warmth extended across greater Sydney, with every one of 16 weather stations with at least two decades of data recording either an all-time high average maximum temperature or a 20-year peak. According to Weatherzone, "Melbourne, Brisbane and Canberra all had one of their top five warmest Junes on record in 2026."
