The Bureau of Meteorology says a severe thunderstorm is likely to produce heavy rainfall, possibly flash flooding, over the next several hours in the Southern Tablelands.
The State Emergency Service advises that people should keep clear of creeks and storm drains; and should not walk, ride a 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.
The State Emergency Service also advises that people should unplug computers and appliances, avoid using the phone during a 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) on 132 500.
The next warning is due to be issued by 5.45pm on Monday, March 20.