The Bureau of Meteorology released the warning to residents on Friday afternoon, with the prediction the storm will last “several hours”.

Goulburn Airport recorded 26mm of rain in just 30 minutes from 1:15 to 1:45pm on Friday, January 11, the bureau said.

“Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding and damaging winds and possibly large hailstones over the next several hours in the Southern Tablelands, South West Slopes, Snowy Mountains, Australian Capital Territory and parts of the Illawarra, South Coast, Central Tablelands, Central West Slopes and Plains and Riverina districts,” the bureau said.

The State Emergency Service has advised residents to: 

* 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 on 131 388, or Endeavour Energy on 131 003 or Essential Energy on 132 080, 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.