‘Slow down’: Dozens of people rescued from cars as heavy rain hammers NSW_1

Emergency services are pleading with motorists to take care after rescuers came to the aid of "13 carloads of people" which became stuck trying to drive through floodwaters on the NSW Central Coast overnight.

The New South Wales State Emergency Service warning comes as the Bureau of Meteorology forecast more wild weather and flooding across NSW on Saturday, with potentially the heaviest rain in 25 years.

"There's always an alternative route, never drive through floodwaters," SES spokesperson Terri Langenemdam said, after carloads of people had to be rescued in the Gosford and Wyong areas (80km north of Sydney) overnight.

"There's also a reminder to keep kids away from creeks, drains and causeways."

The SES has so far received 1600 calls for help.

-with AAP