Flash floods have prompted multiple rescues and calls for help as thunderstorms brought hail, damaging winds and heavy rainfall to areas across NSW stretching to the Queensland and Victorian borders.

Almost 600 NSW SES volunteers were responding to calls for assistance late on Christmas Eve, including 25 separate flood rescue incidents, the bulk of them in the Sydney and Illawarra areas.

NSW SES Acting Assistant Commissioner Allison Flaxman said most of the rescues involved vehicles trapped in flood water.

“We also had several reports of buildings impacted by the flash flooding, with water leaking through roofs and under doors into garages and car parks,” she said.

“SES members assisted with sandbagging and cleanouts.

“Fortunately there were no reports of significant injuries or major damage from the flood rescues.”

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SES volunteers spent Christmas morning continuing to help with clean-up efforts after significant storms ravaged parts of the Northern Rivers, Metropolitan Sydney, Illawarra, South Coast and Riverina.

Sydney copped a hammering on Sunday evening, with the suburb of Little Bay in the city’s east recording 56mm of rain in one hour.

The SES was called to 492 incidents on Christmas Eve, 313 of them across Metropolitan Sydney.

Sunday’s storms were widespread up and down the coast, with hail of up to 10cm in diameter reported in far north New South Wales near the Queensland border.

Thousands of properties lost power in south-east Queensland after supercells rolled across the state on Sunday afternoon.

The Bureau of Meteorology’s Angus Hines said the wet weather would continue for days, including the threat of more severe thunderstorms.

“There is the potential in the atmosphere at the moment for generating these large storms,” he said.

“There’s a chance of thunder or maybe even severe storms for Brisbane, Sydney, Canberra and Melbourne.

“All of those capitals seeing a risk of thundery weather on Christmas Day.”

Acting Assistant Commissioner Flaxman said crews were prepared for a busy stretch and urged people to take care.

“It is critical people assess the conditions of not only their route but their destination before travelling and avoid camping in low-lying areas,” she said.

“If you come across flooded roads, please turn around and find an alternative route.

“Never drive through flood waters.”

She said flood rescue teams have been positioned and prepared for the coming days.

The bureau has issued a flood watch for parts of the south coast through to the Upper Murrumbidgee.

“Heavy rainfall, more intense with thunderstorms, is forecast with a low pressure system expected to move through southern NSW,” the flood alert read.

-AAP