A mother and her six-week-old baby have been rescued from rapidly rising flood waters in Sydney's north-west. 

Dwayne Miller, a volunteer with the State Emergency Service Hawkesbury unit, recounted the dramatic rescue on ABC Radio Sydney.

He was among a group of SES volunteers conducting a routine doorknock in Gronos Point, on the northern banks of the Hawkesbury river, near Wilberforce, on Sunday afternoon when they met a woman who had recently moved to the flood-prone area.

"Unfortunately she wasn't aware of the usual flooding situation of the area," Mr Miller said. "We gave her some advice that she should seek some refuge with some friends because her husband was on the opposite side of the river."

But shortly after the SES members left, the Hawkesbury River began to rise rapidly.

"We came back and grabbed her as quickly as we could, put her in our high-clearance vehicle, our Unimog [all-terrain truck], and drove her across the floodwaters on the other side," Mr Miller told ABC Mornings host James O'Loghlin. 

Mr Miller praised the mother for remaining calm during the emergency, while "the baby slept through the whole thing".

NSW Premier Dominic Perrottet said 83 rescues had been conducted since 9pm Sunday night as the flooding emergency in Sydney and some parts of New South Wales continues.

Thousands of people have been forced to leave their homes across Greater Sydney, with 71 evacuation orders in place and up to 120mm of rain predicted for the city.

Fourth evacuation this year

For the fourth time this year, Emily Kendall has had to evacuate her 40 horses from her Cobbitty property in Sydney's south-west.

Amid flood warnings, Ms Kendall told ABC Radio Sydney they began moving animals from the Sheany Park Performance Horse Centre to other properties on Friday.

"We spent 14 hours evacuating as many horses as we possibly could, we were lucky enough to have a few people who were willing to open their properties and take in a few of our horses to make sure they were well away from the flood waters."

The remaining eight horses were moved to the highest point on the property, which had previously been safe during three earlier floods in March and April.

But on Sunday the waters continued to rise.

"It kept coming higher and higher so we had to do a last minute dash to get the last eight horses out," she said.

"It is definitely the worst this time around and it wasn't supposed to be as severe."

Ms Kendall was hoping for the all clear to return to the property which is currently cut off by flood waters later today, but said it may take until tomorrow.

Five minutes down the road, businesses in Camden that had only recently been repaired or reopened after major floods earlier this year have been hit again.

Camden Mayor Therese Fedeli said there was a sense of "great disbelief" that it had happened again.

"You wake up and think oh no, again."

Ms Fedeli said she knew of at least one restaurant, a caravan park and two petrol stations that had been inundated again.

"What about all those people that probably got all their carpet changed, their furniture? It's happened again."