Heavy rain, which may lead to flash flooding, is possible in coastal areas between Nowra and Narooma from Monday afternoon until Tuesday afternoon.

A trough is deepening near the NSW coast, and is expected to bring periods of heavy rain to the southern NSW coast today and Tuesday.

Rainfall may be enhanced on a local scale by the development of small low pressure circulations within the trough, and thunderstorm activity.

24 hour rain totals in excess of 100mm are likely, with the bulk of this forecast to fall at night.

Locations which may be affected include Batemans Bay, Moruya Heads, Huskisson, Ulladulla and Narooma.

A strong wind warning has been issued for the Batemans Coast on Monday, with a very high chance of rain, mostly in the afternoon and evening.

There is a chance of a late thunderstorm, with southerly winds increasing from 20 to 30km/h, to 30 to 35km/h in the late evening.

The maximum temperature is expected to reach 20°C.

On the waters, winds will be southerly at 15 to 20 knots, turning southeasterly at 20 to 30 knots in the late afternoon.

The first swell will be southerly at 2 to 2.5 metres.

The second swell will be northeasterly at 1 to 1.5 metres.