Police are reiterating pleas for drivers to avoid flooded NSW roads after the body of a man was found in his submerged car in the state’s central west.

The death of the 46-year-old came as much of NSW braced for further inundation, with more than 100 flood warnings in place on Wednesday morning.

The man was last seen at Essington, south of Bathurst, about 11am on Sunday. A search was launched when he failed to return home on Monday.

About 10.30am on Tuesday a police helicopter crew found his car fully submerged in Campbells River at Charlton and State Emergency Service crews recovered the vehicle with his body inside.

“Motorists are reminded not to drive into any roadways covered by water due to the dangers of becoming trapped – if it’s flooded, forget it,” police said in a statement late on Tuesday.

Parts of already sodden NSW are predicted to cop as much as another 65 millimetres of rain by week’s end.

Meanwhile, Melbourne is forecast to potentially break records for its wettest October day, with up to 70 millimetres of rain forecast on Thursday.

In regional areas, some communities have been warned they could be isolated for up to 72 hours as rivers rise and downpours bring flash flooding.

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The Bureau of Meteorology said a trough approaching from the west would bring thunderstorms to the central and southern areas of NSW and Victoria’s north on Thursday and Friday.

Tasmania won’t escape either, with the potential for more than 200 millimetres of rain in the state’s north from Thursday.

Senior forecaster Jonathan How said from late Thursday into Friday, heavy rain would push into Victoria’s north-east and across the western slopes of NSW.

This may cause renewed flooding along rivers in parts of NSW’s central west and south-west and northern and north-west Victoria from Friday, many of which are already full due to heavy rain in recent months.

“But thankfully for those flood-affected communities including Bathurst, Gundagai and Forbes … the heaviest rain will be further south,” Mr How told ABC TV on Wednesday.

“Of course, we are expecting to see some local creek and river rises.”

Across NSW, SES volunteers have responded to more than 1000 calls for help since Friday night.

NSW Emergency Services Minister Steph Cooke said concern for remote communities was high as the “widespread” weather system hit.

“The SES is concerned about many of our rural, regional and remote communities … in Nyngan, Warren, Wee Waa, Gunnedah, Moree, Bathurst and Forbes,” Ms Cooke said.

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But she said emergency personnel were now better prepared than before the previous floods, in March.

She noted 1300 extra volunteers had been added to the emergency service and call-taking capacity had been beefed up.

A three-tier simple warning system for residents has also been put in place and up to 14 night-time helicopters for the state are on stand-by.

Numerous rivers are at major flood levels, particularly in the north and west of the state.

Last month was the fifth highest rainfall on record for Australia as a whole and above average for most of the country, according to the weather bureau.

South of the Murray, the State Emergency Service and BOM are also bracing for flooding in the next few days.

“This event is probably the most significant rain event widespread across the state this year, certainly the most significant in recent months,” BOM senior meteorologist Kevin Parkin said in Melbourne on Tuesday.

“We’ve got a short-term flash flood risk as a result of that rainfall intensity and then a longer-term riverine flooding risk,” he said.

Watch and act flood warnings have been issued for rivers across the state, with the SES urging Victorians not to camp near streams and rivers this weekend and avoid driving to northern parts.

In Queensland, minor flood warnings are current for the Bulloo, Lower Macintyre, Paroo, Bokhara and Barcoo rivers, while northern Tasmania is also set to face heavy rain between Wednesday and Friday, with up to 100 millimetres expected in some parts.

-with AAP