The damaging winds battering parts of the NSW south and central coasts are expected to ease within 24 hours, according to the Bureau of Meteorology.
A deep low pressure system lies off the Illawarra coast and is expected to remain slow moving on Monday, bringing damaging winds, rain and large wind-driven waves along southern parts of the coast.
Wind gusts of 113km/h were recorded at Ulludulla on Monday, while Kiama recorded gusts of more than 95km/h.
Emergency crews are also working to make safe and restore power to 14,500 Shoalhaven homes and businesses affected by the storm.
Endeavour Energy said more than 200 electrical hazards had been reported on its network in the region on Monday, with many people set to be without power overnight due to the scale of the damage, ongoing bad weather and road closures from flooding.
However, these extreme conditions are expected to gradually ease by Tuesday morning as the low weakens, BOM meteorologist Shuang Wang said.
"This system is weakening in trend but is still significant," Ms Wang told AAP on Monday.
"By tomorrow evening there will only be a remnant along the coast as it moves east."
Sunshine will return to Sydney by Wednesday, Ms Shuang said, with a maximum of 19 degrees and a 10 per cent chance of rain.
Earlier the BOM said multiple locations across NSW's south east had recorded more than 100 mm of rain in the 24 hours to 9am on Monday, triggering flash flooding and numerous rescues.
The SES have recorded more than 1000 requests for assistance since Saturday, commissioner Carlene York said, including 560 calls from the northern and central coast areas.
"The weather conditions have created some risk for our community, particularly in relation to damaged roofs, fallen trees and an increased call for sandbagging across the coastal areas," Ms York told reporters on Monday.
"We expect some increased winds...that again will bring risk to trees down and perhaps wires down and impacts on electricity services."
The SES commissioner also said more than 20 flood rescues had been performed since Saturday.
Australian Associated Press