SES volunteers have attended 190 storm-related incidents along the NSW north coast in the past 24 hours, amid heavy rain and winds gusting over 100km/h.
The Bureau of Meteorology issued a coastal hazard warning after a low-pressure system formed off the state's north yesterday.
Volunteers responded to two flood rescues, including one involving two adults and a child stuck inside a vehicle in rising water on Grady's Creek Road, Cougal.
An SES spokesperson confirmed the group was able to escape safely.
SES Superintendent Scott McLennan said the majority of call-outs related to damage caused by wind gusts.
"This is the typical Northern Rivers early spring-summer storm that we're all used to," he said.
"We're noting right across the region that there's been rolling power outages.
"As as the low slowly moves off the coast the rainfall totals we're expecting today and tomorrow will decrease significantly."
Essential Energy estimates more than 3000 residents across the north coast were left without power due to storm damage.
"Crews from outside the affected areas have been brought in to assist local crews to complete repairs and restore power as quickly as safety will allow," a spokesperson said.
More than 20 suburbs across the Northern Rivers remain without power, including Federal, Bangalow, Wilsons Creek, Bangalow, Byron Bay and surrounding areas.
Coffs Harbour has received the heaviest downpours, with about 160mms in 24 hours.
Initial flood watch warnings are in place for parts of the Northern Rivers and Mid North Coast, with a minor-moderate flood warning for the Bellinger River.
Coffs Harbour SES commander Ian Horncastle said volunteers were focused on ensuring rough sleepers were prepared for potential flash flooding in low lying areas of the city.
"It's a concern that we have these people very close to low-lying areas of Coffs Creek and vicinities." Mr Horncastle said.
"Especially as they're not on social media … we do our best to advise them to move out prior to conditions coming, which often in this area happens at night when they're unaware."
A watch and act flood warning has also been issued for Darkwood and Thora as the SES warns residents to prepare to be cut off by rising water.
Ulong General Store owner Steve Cleary said residents had been steadily purchasing supplies in preparation for flooding.
Mr Cleary said his rain gauge had recorded 170mm overnight, but the impacts had so far been minimal.
"It got quite heavy as I was watching the rugby league semi-finals," he said.
"I had to turn the TV up and put on the subtitles on to hear it over the sound on the tin roof."