Source: Bureau of Meteorology

For people in Greater Newcastle, Greater Wollongong and parts of Maitland/Cessnock, Sydney and Wollondilly/Wingecarribee areas.

Issued at 2:39 pm Monday, 20 January 2020.

The Bureau of Meteorology warns that, at 2:40 pm, very dangerous thunderstorms were detected on the weather radar near Camden and Picton. These thunderstorms are moving towards the southeast. Very dangerous thunderstorms are forecast to affect Sutherland, Wollongong and Campbelltown by 3:10 pm and Bundeena and waters off the Royal National Park by 3:40 pm.

Other severe thunderstorms were detected on the weather radar near Branxton, Nowra and Berry. They are forecast to affect Kiama, Newcastle City, Maitland and Raymond Terrace by 3:10 pm and Merewether and Salt Ash by 3:40 pm.

Damaging, locally destructive winds, large, possibly giant hailstones and heavy rainfall that may lead to flash flooding are likely.

The State Emergency Service advises that people should:
* Move your car under cover or away from trees.
* Secure or put away loose items around your house, yard and balcony.
* Keep at least 8 metres away from fallen power lines or objects that may be energised, such as fences.
* Report fallen power lines to either Ausgrid (131 388), Endeavour Energy (131 003), Essential Energy (132 080) or Evoenergy (131 093) as shown on your power bill.
* 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.
* Unplug computers and appliances.
* Avoid using the phone during the storm.
* Stay indoors away from windows, and keep children and pets indoors as well.
* For emergency help in floods and storms, ring the SES (NSW and ACT) on 132 500.