A burst of warm air will sweep over NSW in the opening days of September, possibly giving Sydney its warmest start to spring in more than 50 years. This follows the city’s warmest winter in 167 years of records.

A large high pressure system passing over southern Australia between now and Monday next week will allow a hot air mass to build up over the country’s interior and northwest. As the high moves east of Australia early next week, this hot air mass will spill across NSW and other areas in eastern and southeastern Australia.

This weather pattern is not unusual for spring. However, its timing could see some areas in NSW having their warmest start to spring in decades.

Sydney is currently forecast to reach 24–27°C between Tuesday and Thursday next week, which are the first three days of spring. This is around 4–7°C above average for this time of year.

The last time Sydney reached at least 24°C on the first three days of spring was in 1969. If the city’s temperature manages to climb above 24.8°C between Tuesday and Thursday next week, which is possible, it will be the city’s warmest start to spring in 161 years.

Other areas in eastern and southeastern Australia will also get a taste of the early-season warmth next week.

Maximum temperatures in Melbourne and Adelaide are forecast to reach around 21–22°C next Tuesday, while Hobart should reach about 19°C. These temperatures are about 3–4°C above average for a September day.

Does this mean a warm September?

A warm start to a month doesn’t necessarily mean the whole month will be warm. However, computer models are predicting above average maximum temperatures over most areas of Australia, outside the tropics, in September.

The map below shows one computer model’s prediction for the chance of exceeding the average maximum temperature across Australia this September. The red areas show where maximum temperatures are likely to be above average, while blue shading represents areas where maximums are not likely to be above average.

Image: Chance of having warmer than normal days in September 2026, according to the ECMWF SEAS5 model. Source: Weatherzone.

Image: Chance of being wetter than normal in September 2026, according to the ECMWF SEAS5 model. Source: Weatherzone.

In addition to warmer days outside the tropics, large areas of Australia are also expected to be drier than usual in September, as shown in the map above. This does not mean it won’t rain at all, but many areas of Australia could be drier than they usually would for the first month of spring.

Record winter warmth in Sydney

As of 9am on Friday, August 28, Sydney's running mean seasonal temperature for this winter stood at 15.27°C – around 2.25°C above the long-term winter average and on track to beat the previous record of 14.95°C set in 2013.

This season’s record-breaking warmth was caused by a lack of strong cold fronts over southeastern Australia, which limited cooling in the city. This lack of frontal activity also caused the Australian Alps to have one of their worst snow seasons on record.

Another factor that contributed to the warmth in Sydney this winter was an absence of East Coast Lows. These systems, which are most likely to occur in winter, typically cause several days of cloud and rain over eastern NSW, which suppress maximum temperatures. Without any East Coast Lows, Sydney has had more relatively warm days.

It was also a dry winter for Sydney, with the city only registering 186.2 mm of rain, which is well below the seasonal average of 311 mm.