The NSW State Emergency Service issued a flood evacuation warning on Monday morning for some residents in Lake Conjola town in the wake of heavy rain that has lashed parts of the state.

Rising flood water broke the banks at Lake Conjola early on Monday morning.

Early on Monday morning the SES told residents within the Lake Conjola Entrance Tourist Park, Deep Water Resort, Edwin Avenue, Aney Street, Milham Way, Gerrard Way, Carroll Avenue and Lake Conjola Entrance Road should prepare to evacuate within the next two hours.

Residents were advised to go and stay with family or friends, or make other arrangements. An evacuation centre has been set up at the Ulladulla Civic Centre.

The SES advised that once floodwaters hit 1.5 metres, road access would be cut and people may be trapped.

Lake Conjola was hit earlier this year when the Currowan fire claimed almost 90 homes in the community.

The fire swept through the town on New Year's Eve and was finally extinguished on the weekend after burning almost 500,000 hectares in 74 days.

Lake Conjola's volunteer recovery unit waded through waist-deep water on Monday to ensure supplies for bushfire-affected victims are safe.

Lake Conjola recovery centre co-ordinator Peter Dunn said the team saved all the items from the risk of damage.

"We have had to push stuff up off the floor in some of our areas," he said, while wading through water to speak with affected residents.

"We've got material that is needed and given to families. That's been moved, that's all in good shape as long as we don't get too much more [rain] then we should be right."

The Bureau of Meteorology issued a severe weather warning for South Coast and parts of Northern Rivers, Mid North Coast, Hunter, Metropolitan, Illawarra and Snowy Mountains at 11.20am.

"Heavy rain, which may cause flash flooding and riverine flooding, is possible for the southern parts of the South Coast and Monaro Country this morning and early afternoon, easing later this afternoon," the bureau warned.

It also warned of damaging winds averaging 60 to 70 km/h, with gusts in excess of 90 km/h, along the coastal fringe south of Batemans Bay, and damaging surf conditions with waves exceeding five metres in the surf zone, may produce significant beach erosion south of Batemans Bay for areas exposed to the east.

The surf conditions are expected to ease this afternoon or evening, although hazardous surf will persist into Tuesday, the bureau said.

Abnormally high tides are expected at Tuesday morning's high tide for the entire New South Wales coast.

An Ulladulla SES Unit spokesperson said a flood rescue crew was stationed at Lake Conjola and they also had a presence on the ground. Other crews continue to do reconnaissance work at Burrill Lake and Lake Tabourie.

Earthmoving equipment was used to open Lake Conjola's entrance to the sea on Monday morning.

"To minimise the potential danger to operational staff the lake has been opened before the next high tide reaches its peak," the Shoalhaven City Council said in a statement.

"Residents in Lake Conjola are requested to stay outside the work area and keep away from the edges of the dug channel and eroding banks following opening as these areas are very unstable and unsafe.

"It is expected that the low-lying areas around the lake will be subject to flooding and people should put in place their flood emergency plan."

More than 100mm has fallen in the Milton-Ulladulla district since 9am on Sunday. SES advises people should stay clear of driving through floodwaters.

A possible thunderstorm is forecast for the region on Monday afternoon.

READ MORE: Live updates on the Shoalhaven floods

Further inland, roads near Braidwood were closed due to flooding.

Braidwood has received more than 96mm of rain since Sunday, according to the Bureau of Meteorology. The mean rainfall for Braidwood in the month of February is 67.4mm.

Queanbeyan-Palerang Council said roads and bridges that were "impassable" included River Forest Road, Charleys Forest Road, Jembaicumbene Bridge, Back Creek Bridge, Northangera Road, Lyons Creek Bridge on Monga Road, Torpys Lane off Little River Road and the temporary crossing at Pigeon Gully Bridge.

Those areas were affected by the Charleys Forest fire, which was officially set to extinguished on Sunday.

The Charleys Forest fire formed on the western flank of the Currowan fire after it had crossed into the NSW RFS Lake George Zone in December.