Destructive winds, which reached 120 km/h in some parts, caused significant damage, bringing down trees, powerlines and tearing roofs off homes.
More than 1,200 NSW SES volunteers have been active responding to calls and assisting communities across the state, with more than 1,100 incidents reported in the last 24 hours.
NSW SES Assistant Commissioner Sean Kearns urged people not to become complacent.
"More thunderstorms are likely this afternoon, with heavy rain and strong winds expected in the Mid North Coast, Northern Rivers and Northern Tablelands" Assistant Commissioner Kearns said.
"We know this time of year brings storms that are fast-moving but intense, and we want people to be prepared for the impacts of these summer storms."
"Crews will continue to assess damage and attend to repairs as soon as it is safe to do so. More than 45,000 homes across NSW are still without power, so it will need to be isolated before our crews can move in and begin clean up work."
It comes as the Bureau of Meteorology officially declares a weak La Nina pattern for summer, which is likely to be short lived.
While storms and flash flooding can happen at any time, La Nina weather patterns can bring above average rainfall.
"It is important to know your storm and flooding risk, have a plan in place, get your home ready, be aware of what you will do if disaster strikes, and look out for one another," Assistant Commissioner Kearns said.
"Stay across local warnings and information in your area by downloading the Hazards Near Me app and please steer clear of floodwater - If you encounter a flooded road, turn around and find an alternative route."
"The NSW SES remains ready to respond to any future weather events and we've boosted operational capabilities through training and rescue assets in the past 12 to 24 months."
In Metropolitan Sydney, a large number of jobs were concentrated around the Blacktown and Parramatta areas, where clean-up efforts are continuing.
NSW SES crews also responded to a surge in calls for assistance in the Central West, particularly around Bathurst, Dubbo and Orange, where a significant amount of property damage has been recorded.
If you are calling the NSW SES on 132 500, please be patient and we will get to your call.
If you're in a life-threatening situation, please call Triple Zero.
OPERATIONAL STATISTICS:
Statewide incidents in the 24 hours to 2pm Thursday 27 November
Total: 2,031
By Zone:
Metro Zone: 1,125
Northern Zone: 466
Western Zone: 178
South Eastern Zone: 106
North Western Zone: 96
Southern Zone: 23
North Eastern Zone: 33
SAFETY MESSAGES:
- Please do not approach fallen powerlines.
- If it is safe to do so; secure and put away and loose items in your backyard or balcony.
- Park cars undercover and away from trees and powerlines
- If your roof or balcony is struck by a fallen tree, branch or other large debris - stay clear and remain indoors if you can. It may have been structurally weakened, even if there is no obvious damage.
- Have your emergency kit and grab and go bag handy in case you lose power.
