Heavy widespread rain has led to dangerous flash flooding across much of NSW as more people are told to evacuate from rising waters that have left some towns isolated.

In the 24 hours to Monday morning, the NSW State Emergency Service had responded to 33 flood rescues and 462 requests for help.

The SES said a rescue was underway for a man trapped in his car in the central-western town of Alectown, who called for help just before 4am on Monday.

Police and Rural Fire Service personnel have spotted the vehicle and a helicopter has been deployed to help rescue the man.

Meanwhile, people in low-lying parts of the central-western town of Canowindra have been urged to evacuate immediately because of high river levels and dangerous flash flooding.

An evacuation centre has opened at the local public school after the town recorded 99mm of rain in just six hours overnight.

The historic town of Molong, in the Central Tablelands near Orange, is completely isolated by floodwaters, with flash flooding making it too dangerous to evacuate.

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The SES is warning people in Molong’s low-lying areas to move to higher ground.

An evacuation centre has been opened at the RSL club, while an ADF helicopter has been sent to help rescue people trapped in flood water and help with medical retrievals.

In the southern border town of Albury, the SES was called to rescue two children playing in a storm water drain on Sunday, while at the central-western town of Woodstock the SES helped rescue people from six vehicles after a bridge was washed away.

The Bureau of Meteorology has cancelled a severe thunderstorm warning for the mid-north coast, the Hunter, the Central Tablelands, the northwest slopes and plains, the central-west slopes and plains, upper western and Northern Tablelands districts.

The bureau says the immediate threat of severe thunderstorms has passed, but the situation will be monitored and further warnings issued if necessary.

SES Assistant Commissioner Nicole Hogan said flooding would continue to affect multiple communities in inland NSW this week.

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The Lachlan River was rising at Forbes and the SES continues to support the community as people there recovered from the recent inundation, she said.

The SES has delivered supplies of food, medicine and animal feed to 1000 to residents cut off by floodwaters since severe weather began in mid-September and carried out 500 flood rescues.

SES Commissioner Carlene York said the volunteer workforce was fatigued and personnel have been requested from other states.

Flooding continues across western and southern NSW, in towns including Collarenebri, Walgett, Bourke, Condobolin, Hay and Albury.

© AAP 2022

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