A spectacular waterspout tore across a bay in NSW, Australia, on Sunday afternoon as residents cleaned up after a weekend of wild weather.

A waterspout is a large rotating cloud that can only move across a body of water.

A senior meteorologist at Australia's Bureau of Meteorology, Peter Zmijewski, said specific conditions were required for a waterspout like Sunday's on Bateman Bay to form. The air needed to be unstable, the water warm compared with the air and there needed to be wind shear to initiate it, he said. They do not suck up water.

''They are impossible to forecast,'' he said. ''They can be dangerous if in the vicinity, on a surfboard or swimming, but you would have to be very unlucky.''

About 24,000 lightning strikes were recorded in NSW over the weekend, the majority in the state's north.

The Bureau of Meteorology said the state's highest rainfall was recorded at Coffs Harbour, with 160 millimetres falling in the 24 hours to 9am Sunday. Wind gusts of up to 100 kmh were also recorded in the state's north.

Local emergency services were kept busy with 150 calls for help received, mostly from the northern NSW township of Woodburn, just south of Ballina, where at least four homes will have to be demolished after they were severely damaged in the storm.

The State Emergency Services local controller, Jim McCormack, said it was a ''miracle'' no one was seriously injured during the storm.

- Sydney Morning Herald and AAP

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