A severe thunderstorm warning for heavy rainfall and damaging wind has been issued for the Hunter and many parts of the state.
The Bureau of Meteorology said the rain may produce flash flooding in the warning area over the next few hours.
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 clear of fallen power lines.
* 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 and 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.
Overnight storm brings cooler weather for Christmas
A SPECTACULAR electrical storm struck Newcastle about 10.30pm last night, rattling the city with heavy rain, thunder and lightning.
The storm brought with it a southerly change that will provide some Christmas Day respite from yesterday’s sweltering heat.
Temperatures reached 38.2 degrees at Singleton yesterday, while Newcastle University recorded 34.5 degrees at 3pm.
Today was expected to be cooler, with a chance of thunderstorms in the evening.