Wild storms pummel the coast of New South Wales overnight

Wild storms have lashed the NSW coast with floods and gale force winds wreaking havoc on homes.

The NSW State Emergency Service (SES) has responded to more than 1450 calls for help, with the majority of requests coming from the greater Sydney region.

At least one person has had to be rescued from floodwaters at Parramatta, in Sydney's west, while others have been pulled out of stranded cars in other parts of the state.

"These jobs are a reminder to never drive, ride or walk through flood water," said SES spokeswoman Stephanie Wills on Monday night.

Destructive winds and heavy rainfall have also battered the Illawarra and Hunter regions in an unusually large storm for this time of year.

Ms Wills said the storm, which was outside the normal season between October and March, has inundated volunteers.

"It's unusual, but the weather is unpredictable," Ms Wills told AAP.

More than 17,000 houses lost power throughout Sydney and the Hunter region, while Fire and Rescue NSW have deployed crews to the Central Coast as the weather worsens.

Three extra tankers have been moved to Sydney's northern beaches.

Many roads have closed due to flooding, with warnings in place for coastal regions from the Manning Valley to the Central Coast.

The Bureau of Meteorology has warned gale force winds of up to 100km/h will continue on Tuesday with high rainfall and heavy surf also predicted.