Maximum wave heights nearing six metres were recorded near Sydney on Wednesday morning as cold and blustery southerly winds caused a sharp temperature drop along Australia’s east coast.
The satellite images below show a large field of speckled cloud spreading over the Tasman Sea on Wednesday morning. This cloud pattern is a typical feature in the cooler months of the year and occurs when cold Southern Ocean air moves over comparatively warmer waters in the mid-latitudes.
This cold Southern Ocean air is being driven north by a surge of strong southerly winds sandwiched between a high pressure system centred over the Great Australian Bight and a low pressure system near New Zealand.
Big waves hitting NSW coast
The powerful winds blowing over the Tasman Sea are generating large waves along the NSW coast.
A waverider buoy located off the coast of Sydney’s Northern Beaches registered a maximum wave height of 5.7 metres early on Wednesday morning. Further north, 5.9 metre waves were also detected near Crowdy Head at 9 am AEST.
Wave heights will increase along the northern half of the NSW coast and in southeast Qld on Wednesday afternoon into Thursday morning.
A hazardous surf warning is in place for the Hunter Coast and Sydney Coast on Wednesday, meaning surf and swell conditions are expected to be hazardous for coastal activities such as rock fishing, boating, and swimming.
Windy and cold along the coast
The blustery southerly winds that are whipping up large waves in the Tasman Sea are also causing temperatures to plummet along Australia's east coast.
Wind gusts reached 100 km/h at Gabo Island, 80 km/h at Green Cape and 76 km/h at Wattamolla early on Wednesday morning. Gusts also reached 72 km/h at Cape Byron shortly before 5:30am on Wednesday as the southerly change swept along the north coast of NSW before continuing into southeast Queensland.
Image: Forecast wind gusts at 7 pm AEST on Wednesday, September 16, 2026. Source: Weatherzone.
Sydney’s apparent temperature, which accounts for the impact of wind chill, was around 5°C at 8am on Wednesday, while Byron Bay felt like 10°C at 8:30am.
Looking ahead, the southerly change will continue moving towards the north on Wednesday and Thursday, causing showers and cooler southerly winds to spread up the central and north coasts of Queensland.
Conditions will ease along the east coast during Thursday and Friday as the high pressure system moves across southeastern Australia from the Bight. This will allow wind and waves to ease as temperatures rebound and quickly warm up for the weekend.
Sydney’s maximum temperatures are forecast to jump from 17°C on Wednesday to 28°C by Saturday. Brisbane is predicted to reach 24°C on Thursday and Friday but could warm to 30°C on Saturday. This temperature see-saw is a typical feature of spring along Australia’s east coast.