Sydney records hottest June since 1859 as expert warns new high a ‘signature’ of global warming | Australia weather

Sydney officially experienced its warmest June since records began, following a spring-like warm winter.

While initial weather data suggested the month was simply one of the hottest, the Bureau of Meteorology confirmed on Friday that June 2026 had broken the all-time average temperature record at Observatory Hill, where monitoring first began in 1859.

The month is marked by 15 consecutive days with maximum temperatures of at least 20°C between 7 and 21 June. This surpassed the previous June record of nine consecutive days in 1919.

Sydney’s overall average temperature – the standard measurement for temperature records averaged each day – reached a record-breaking 16.1°C in June, eclipsing the previous record of 15.7°C in 1991, according to a bureau spokesman.

While the average maximum (20°C) and minimum (12.2°C) were both technically the second highest individually recorded, their sustainable, non-seasonal consistency was enough to ensure June 2026 was the warmest place overall.

Sydney-based climate scientist Prof Andy Pitman said it was “not a complete surprise” at the new record.

“There are traces of global warming all over it,” Pitman said. “There is no more leeway with the heat… We know that warming is driven by the failure of governments around the world to profoundly reduce emissions.”

‘warming point’

Record-breaking ocean temperatures off the NSW coast are keeping Sydney warm, experts say.

Prof Matthew England said the ocean was becoming a global “warming hotspot” with rapid temperature increases.

“The fundamental balance in our climate system is that the oceans absorb a lot of heat in the summer and radiate that heat back into the atmosphere in the winter,” said the UNSW oceanographer and director of the ARC Center of Excellence for Our Future Oceans.

“The very warm oceans off Sydney will be a significant contributor to the record warmth we have achieved this winter.”

Normally southerly winds bring cold air to the coast. But Britain noted that this airflow absorbed the surface heat of the ocean as it passed over the abnormally warm Tasman Sea, dulling the cold when it reached Sydney.

‘A false sense of security’

On land, vegetation that must lie dormant during the winter months is “happily blooming” and drawing moisture from the soil, Pitman said.

“Moving soil moisture into the atmosphere and drying it out increases warming due to CO2, leading to dry springs and increased fire risk unless we see enough rain,” Pitman said.

“The big issue here is not that a lot of people in Sydney enjoy a warm winter. It’s downriver in the spring and summer when things are drier than they should be.”

While a milder winter may seem welcome, England said the “real cost of top-level events is heavy”.

“People can be lulled into a false sense of security.”

The risks of upcoming heatwaves and bushfires will greatly increase as El Niño pushes moist air away from eastern Australia.

With a recent NSW Net Zero Commission Pitman called for urgent action, producing a report highlighting serious gaps in climate adaptation.

“The climate science community has been warning about this since at least 1995,” he said. “There is a need for serious emergency planning against extreme heat.

“I don’t think Australia was prepared for the kind of heat it was going to encounter.”

Unseasonable heat has spread across Sydney. Each of 16 weather stations with at least twenty years of data all-time highest average maximum temperature or 20 year peak.

The heat has spread far beyond NSW. Accordingly Air Zone: “Melbourne, Brisbane and Canberra experienced one of the five warmest Junes on record in 2026.”