A strong wind warning is in place for the Illawarra coastline, with a severe weather weather warning for heavy rain and damaging winds in areas south of Nowra.

Further south the weather is expected to deteriorate, with up to 200mm of rain possible across Tuesday and Wednesday, particularly in areas around the lower South Coast and Moruya.

"The two major concerns for us are the Bega River which is forecast for a potential moderate rise, and the Moruya River which is forecast for a minor," SES Chief Superintendent Dallas Burnes said.

SES has sent personnel, aviation and high clearance rescue vehicles to these areas.

"We are concerned about the potential for riverine or flash flooding," Mr Burnes said.

"All those local catchments and systems are at risk of quick flash flooding and quick rises due to the heavy nature of this forecast."

There are weather warnings current for 11 areas across NSW.

From Wednesday, localised rain and strong winds will move towards the coast, with damaging winds up to 90km/h expected in Moruya from late Wednesday morning.

"Over the next 24 to 36 hours we're looking at sustained heavy rainfalls across the state," Mr Burnes said.

Flash flooding and water pooling on roads is possible during this weather pattern, not extended riverine flooding experienced during 2022.

People are urged not to travel in areas of heavy rainfall and keep up-to-date with weather warnings.

"The best rescue we do is the one we don't have to do because the community is making really sensible decisions," Mr Burnes said.

"You really do not know what's under that water, even though it's a road you may have crossed earlier in the day."

For emergency help with floods or storm damage call the SES on 132 500. For life-threatening emergencies call triple-0.