The 28-year-old went missing late on Sunday after a vehicle was swept off a causeway at Cooyal Creek at Gulgong, north of Mudgee.

Three people, including the 45-year-old male driver and two male passengers, escaped the vehicle, but the woman was swept away.

After an extensive search, police say a body was found on the riverbank at 9:50am on Monday.

Some 122 SES warnings are in place across the state, including 20 emergency evacuation warnings.

Some 43 local government areas are subject to a natural disaster declaration.

More than 550 SES members in the field have taken 482 requests for help and carried out 37 flood rescues in the past 24 hours.

More crews are arriving from WA to lend a hand on Monday.

A severe weather warning that covered much of NSW was cancelled on Monday despite the Northern Rivers town of Alstonville receiving 233mm of rainfall in a 24-hour period, and multiple other areas receiving more than 100mm.

NSW wheat farmers expect the bill from flooding rain that has wiped out wheat crops in the northwest of the state to reach hundreds of millions of dollars.

Agronomists have estimated “conservative” losses of 120,000 hectares of wheat with an estimated value up to $192 million as a result of widespread flooding in the Moree, Walgett and Narrabri areas.

It has prompted fresh calls for urgent financial support for farmers impacted by flooding who want emergency funding allocated in Tuesday’s budget.

NSW Farmers Grains Committee Chair Justin Everitt said some farmers were calling it a “wet drought”, and while it is unlikely to impact food prices in the short-term, he said for some growers it will be a financial disaster.

“You spend all this money preparing your paddocks – sowing your crops, fertilising and spraying them – only to see them wiped out a couple weeks before harvest. It’s heartbreaking,” Everitt said.

“It’s a big turnaround in fortune from the big bumper harvest ABARES (Australian Bureau of Agricultural and Resource Economics) was predicting a couple of months ago.”

“We’ve had a huge crop across the state in those places where people could get on paddocks to sow, but now that’s all under threat too.”

Grain farmer Matthew Madden received 243 millimetres of rain between Wednesday and Friday last week at his farm 25 kilometres west of Moree, and remains cut off from the town.

Madden, also a director of Grain Producers Australia, is expecting downgrades on his wheat while others will face “catastrophic losses.”

He said normally the rainfall wouldn’t have done the damage it had done, but it had fallen in already-full catchments.

“Very preliminary assessments done found at least 120,000 hectares of crop could be lost, my personal belief is that that could that could be conservative,” Madden said.

He said there will also be other associated costs, for example for contractors who won’t be able to harvest, as well as the damage done to infrastructure.

Madden said only three years ago he had witnessed the driest year on his property and now it is the reverse.

“2019 was the worst we’d ever seen, and now it’s the highest water level, all in three years,” he said.

-with AAP