SES volunteers across NSW responded to 278 calls for emergency support on Sunday night and Monday morning.
About a third were from metropolitan Sydney and the rest from central parts of the state, where residents experienced heavy winds, lightning and rain throughout the night.
The small town of Carinda near Tamworth was hit hard.
The pub, pizza shop and general store sustained damage, and multiple houses were left without power as winds downed power poles.
Happy Monday, — Bureau of Meteorology, New South Wales (@BOM_NSW) #NewSouthWales! Here's your forecast:⛈� Showers and thunderstorms over the north-east, possibly severe.🌦� Isolated afternoon showers elsewhere in the east.☀� Dry and sunny over the southern inland.Details: https://t.co/UqlGxUsuBw pic.twitter.com/5Qo0wY1auONovember 17, 2024
Walgett Shire Mayor Jasen Ramien said the lightning and winds had brought fires to the region before the downpour.
"From all reports, Carinda is in a fair mess," he told ABC Breakfast on Monday.
"There's been damage to multiple buildings right across the town ... homes damaged, shops."
Mr Ramien said he had declared a disaster in the area, opening residents up to state government support.
Areas in the state's Central West including Bathurst, Mudgee and Dubbo also experienced heavy rain with calls for emergency help.
A limited number of homes remain without power across the state, while several cars were damaged in Sydney as a steel road plate was dislodged during the storm.
Transport for NSW secretary Josh Murray apologised to motorists on Monday morning, saying they would be compensated.
"It was a nightmare," Mr Murray told 2GB.
"Let me apologise to anyone whose car was damaged or anyone else who was caught up for about two hours."
The Bureau of Meteorology said 20 to 40mm of rain fell across areas of the state overnight but Victoria also experienced heavy rain.
"We did see some isolated higher falls pushing up to 50 or 60mm, most notably through parts of northeastern Victoria, the top total between nine o'clock Sunday morning and six o'clock Monday," Senior Meteorologist Miriam Bradbury said.
Ms Bradbury said the region had likely seen the worst of the storms and conditions were generally forecast to ease across the country.
In October, 20,000 residents of Broken Hill in far western NSW were left without power for almost a week after storms tore through the town and downed transmission towers.
Back-up generators failed to carry the load of the town, forcing the state government to intervene and provide compensation for businesses and residents.
Investigations are ongoing into potential failures by network operator Transgrid.
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