NSW residents warned of flood risk as heavy rain and storms lash state

A severe weather warning has been issued for parts of NSW today as heavy rain and storms pummel the state.

The Bureau of Meteorology is warning of heavy falls in the Hunter and Mid North Coast regions over the coming hours. Severe thunderstorms are possible across the north-east, with a risk of heavy rainfall, large hail and damaging winds.

Rainfall totals of 20mm to 40mm are likely, but slow-moving thunderstorms could bring heavier falls of 70mm to 80mm, forecasters say.

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A severe weather warning has been issued for heavy rainfall to develop about the Barrington Tops through today. Falls could reach a maximum of 95mm in isolated parts.

Minor flooding is possible along the Paterson and Williams rivers from tonight and into tomorrow. The Manning and Gloucester, Goulburn and Hunter rivers as well as Wollombi Brook could also see flooding tomorrow.

The deluge is being driven by a broad low-pressure trough deepening to a low pressure system over southern Queensland and northern inland NSW today.

NSW SES Assistant Commissioner Colin Malone says flash flooding was a risk with thunderstorms that can happen quickly, without much warning.

"We remind the community to steer clear of flood water. If you come across a flooded road, turn around and find an alternative route," he said.

"Our crews are well prepared to respond and have been put on standby across the state, but we're asking the community to do their bit and not take any unnecessary risks."

Malone urged communities to stay up to date with the latest information and warnings.

There are also flood warnings in place across Tasmania, with the bureau warning minor flooding is possible this morning along the South Esk River at Fingal and at Llewelly in the state's north-east overnight.

During the weekend, rain is expected to ease as the weather system moves offshore.