Source: Bureau of Meteorology

For people in parts of Sydney and Gosford/Wyong areas.

Issued at 3:09 am Wednesday, 18 March 2026.

Slow moving thunderstorms producing heavy, locally intense rain along the central NSW coast.

A southerly change has been moving up the coast and triggering heavy rainfall in a moist atmosphere. The heaviest rainfall is occurring in northern Sydney.

The Bureau of Meteorology warns that, at 3:10 am, a VERY DANGEROUS THUNDERSTORM likely to produce heavy, locally intense rainfall that may lead to dangerous and life-threatening flash flooding was detected near Dee Why and Collaroy. This thunderstorm is moving towards the north. It is forecast to affect Mona Vale, Terrey Hills and Avalon Beach by 3:40 am and Palm Beach by 4:10 am.

The State Emergency Service advises that people should:
* Keep clear of creeks and storm drains.
* Don't walk, ride your bike or drive through flood water.
* If you are trapped by flash flooding, seek refuge in the highest available place and ring 000 if you need rescue.
* Stay indoors away from windows, and keep children and pets indoors as well.
For emergency help in flood and storms, ring the SES on 132 500.
Stay updated on the Hazards Near Me NSW app or the ACT ESA website (https://esa.act.gov.au).