Sydney has officially experienced its hottest June since records began, after a winter month of spring-like warmth.
While early weather data suggested the month was merely among the warmest, the Bureau of Meteorology confirmed on Friday that June 2026 broke the all-time mean temperature record at Observatory Hill, where tracking first began in 1859.
The month was marked by 15 consecutive days with a maximum temperature of at least 20C between 7 and 21 June. This overtook the previous June record of nine consecutive days in 1919.
According to a bureau spokesperson, Sydney’s overall mean temperature – the standard metric for heat records that is the average across each day – in June hit a record-breaking 16.1C, eclipsing the previous 1991 record of 15.7C.
While the average maximum (20C) and minimum (12.2C) both technically ranked as the second-highest on record individually, their sustained, unseasonal consistency was enough to secure June 2026 its place as the warmest overall.
Prof 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.”
‘Warming hotspot’
Experts said record-breaking ocean temperatures off the NSW coast had kept Sydney warm.
Prof Matthew England said the ocean had become 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,” the UNSW oceanographer and director of the ARC Centre of Excellence for Our Future Oceans said.
“Those very warm oceans off Sydney would be a significant contributor to the record warmth we’ve had this winter.”
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Normally, southerly winds bring cold temperatures to the coast. However, England noted that as this air flow passes over the abnormally warm Tasman Sea, it absorbs the ocean’s surface heat, blunting its chill by the time it reaches Sydney.
‘A false sense of security’
On land, Pitman said vegetation that should be dormant during winter was “happily transpiring”, drawing moisture out of the soil.
“Moving soil moisture out into the atmosphere and drying … amplifies the heating due to CO2 and unless we see decent rain, leading to dry springs and elevated fire risk,” Pitman said.
“The big issue here is not that lots of people in Sydney are enjoying a warm winter. It’s downstream in spring and summer, when everything is drier than it should have been.”
While a milder winter might feel pleasant, England said “the actual cost of high-end events is severe”.
“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.
With a recent NSW Net Zero Commission report highlighting severe gaps in climate adaptation, Pitman urged immediate action.
“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.”
The unseasonal warmth extended across greater Sydney. Of the 16 weather stations with at least two decades of data, every single one recorded either an all-time high average maximum temperature or a 20-year peak.
The heat extended well beyond NSW. According to Weatherzone: “Melbourne, Brisbane and Canberra all had one of their top five warmest Junes on record in 2026.”
