Heavy rain battering NSW's south coast is set to intensify, with the downpours on already wet ground increasing the risk of flash flooding.
A severe weather warning issued by the Bureau of Meteorology impacts a large part of the coast from Kiama down to the area north of Bega and inland ranges.
Heavy rainfall could lead to flash flooding on Saturday and continue into Sunday, the weather bureau warned.
It's likely 24-hour rainfall totals could reach as high as 160mm in some areas while isolated parts of the ranges are expected to receive up to 200mm.
"This is rain falling on already wet ground so the water will pool and cause flash flooding so if you're in these areas please take care," meteorologist Christie Johnson said.
Nowra, Batemans Bay, Moruya Heads, Ulladulla, Narooma and Araluen are expected to be hardest hit.
SES NSW has already responded to 240 incidents in the 24 hours to 3pm due to wet conditions in the Illawarra, South Coast and Sydney areas.
Flash flooding forced some roads to close and the Warragamba Dam in Sydney's west is at capacity and is expected to spill, according to Assistant Commissioner Nicole Hogan.
"No significant flooding consequences are expected, however, people downstream of the dam are warned that fast-flowing or deep water near waterways and floodplains may be hazardous," she said.
Ms Johnson urged anyone living near streams or rivers to pay particular attention to alerts over the weekend.
Initial moderate flood warnings are in place for the Moruya and Deua rivers, with wet conditions expected to peak on Sunday morning.
Flood watch alerts have also been issued for Hawkesbury Nepean Valley, St Georges Basin, Bega and Moruya catchments which are already wet due to recent rainfall.
"Now this is an evolving situation, the rain is already falling," Ms Johnson said.
"We are expecting it to increase, the heaviest rain is likely on Saturday afternoon and night into Sunday morning."
Meanwhile, a bushwalker has survived after spending a night lost in the Blue Mountains as the area was pummelled by heavy rain.
The 38-year-old was reported missing at 11.30am on Friday and was found by a team of specialist search and rescue professionals just under 24 hours later, SES NSW said.
Senior group officer Caro Ryan said the woman was not injured and was checked over by paramedics before walking out of the bush with the rescuers.
"We located her in bushland near Katoomba and helped warm her up because she had been out in the cold and rain overnight," Ms Ryan said.
"We know the areas people often get lost, the mountain passes and the tricky pinches."
