6:28PM UPDATE: Severe thunderstorms are no longer occurring in NSW and the ACT.

The imminent threat of severe thunderstorms has passed, but the situation will continue to be monitored and further warnings issued if necessary.

The State Emergency Service advises that people should: keep clear of fallen power lines, keep clear of creeks and storm drains, don't walk, ride your bike or drive through flood water and for emergency help in floods and storms, ring the SES (NSW and ACT) on 132 500.

A SEVERE thunderstorm warning has been issued for the South Coast and parts of the Southern Tablelands and Snowy Mountains Forecast Districts.

The Bureau of Meteorology issued the warning at 3.45pm Friday.

Severe thunderstorms are likely to produce large hailstones and heavy rainfall that may lead to flash flooding in the warning area over the next several hours.

Locations that may be affected include Batemans Bay, Eden, Bega and Moruya Heads. 

The State Emergency Service advises that people should: 

* Move your car under cover. 

* 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. 

The next warning is due to be issued by 6.45pm.