Utility provider Ausgrid hopes to restore power to thousands of homes and businesses across Sydney and the Central Coast by the end of the weekend, after receiving some extra help to clear storm debris.
The state government will deploy more than 100 additional staff from State Emergency Service, Rural Fire Service and Fire & Rescue organisations to help from Thursday, as almost 30,000 Ausgrid customers remain without power.
Repair crews from other NSW energy providers and interstate have also been assisting, with more to arrive on Thursday morning.
Forecast rainfall threatens to cause the state further damage, with the Bureau of Meteorology issuing a severe thunderstorm warning on Wednesday for the northern rivers and northern tablelands regions, and parts of the Hunter, mid-north coast, central tablelands and north west slopes and plains.
Meanwhile, a moderate to major flood warning remained in place for the Orara River at Glenreagh and Coutts Crossing, northwest of Coffs Harbour.
A very high chance of showers is forecast for Sydney, with 20-40mm possible on Thursday.
The NSW coast was drenched over the weekend, with up to 550 millimetres of rain falling across parts of the northern rivers, mid-north coast, Central Coast, Sydney, Blue Mountains and the Illawarra.
Water Minister Melinda Pavey said the rainfall had provided relief to parts of the state but regional NSW was still in drought.
"While the rain has been a welcome relief, it unfortunately has resulted in flooding and has fallen below the catchment areas of our key inland storages," Mrs Pavey said in a statement on Wednesday.
"The positive is the ongoing heavy rains in the Gwydir Namoi Valleys, as part of a wider rainfall pattern that is continuing to push flows into the Barwon-Darling system."
Ausgrid on Wednesday night said power had been restored to 112,000 customers after "one of the worst storms to hit our network in the past 20 years", but about 28,000 customers remained without.
"With additional support to clear fallen trees we are aiming to have all customers restored by the end of the weekend," Ausgrid said in a statement.
Emergency services were on Tuesday left to clear fallen trees, remove debris and extract cars from floodwaters around the Harbour City.
Ausgrid confirmed it had asked all levels of government for assistance, particularly for tree-clearing services.
"The quicker we clear vegetation the quicker we can get our customers connected," it said.
The company had earlier raised the prospect of receiving Australian army help to clear storm debris.
Meanwhile, Endeavour Energy said there would be fewer than 50 homes still without power on Wednesday night, predominantly in remote townships north of the Hawkesbury River.
"Our plan is to access these areas tomorrow via the Central Coast so all customers will have their power back on tomorrow night," an Endeavour statement said.
The Electrical Trades Union earlier in the week said post-storm recovery efforts had been hampered by up to 5000 job losses since 2015 at energy providers Ausgrid, Endeavour Energy and Essential Energy.
The union blamed these losses on the NSW government's "privatisation agenda" and imposed Australian Energy Regulator cuts.
NSW Energy Minister Matt Kean accused the union of lying.
"There are more full-time equivalent workers in Ausgrid today than there were when the institution was privatised," Mr Kean said told Sky News on Wednesday.
"So let's get the facts on the table and stop the ETU pushing their political agenda ... we want to make sure people get connected as soon as possible."