There were snowboarders in Newtown, ice floating down the Parramatta River and snowmen in Rose Bay.

As the blankets of hail that fell across Sydney lingered on Sunday morning, the Bureau of Meteorology is predicting warmer and calmer conditions across the city this week.

Bureau of Meteorology forecaster Zach Berry-Porter said a high pressure system over the Great Australian Bight is predicted to produce temperatures of up to 20 degrees.

"It's looking like it will be a quieter period for weather," Mr Berry-Porter said.

"Something that will become a feature is colder mornings for Sydney."

The lowest predicted minimum temperature in Sydney is 13 degrees, while showers are forecast for the second half of the week, according to the bureau's website.

Mr Berry-Porter said the hail storm on Saturday afternoon - which produced small stones in intense showers - was caused by cold air in the upper level of the atmosphere.

A second storm band moved from the Blue Mountains to Sydney later in the evening.

"It was pretty unusual to get such a large quantity of hail but we are moving towards a cooler season and hail is more likely to survive and reach the ground."

The bureau on Sunday issued a marine wind warning for Macquarie coast, Hunter coast, Sydney coast, Illawarra coast, Batemans coast and Eden coast.

Sydney and Blue Mountains residents posted pictures on Saturday afternoon of whitened roads, cars wheel-deep in hail, and a hail-coated Parramatta football stadium.

The roofs of several large factories in Huntingwood, an industrial suburb in Sydney's west, collapsed during the hail storm.

The neighbouring suburb of Blacktown received 60mm of rain in an hour, while 60mm fell at Prospect Reserve, Mr Berry-Porter said.

Meanwhile, clean up efforts continue after the major storms earlier in the week.

Ausgrid said its workers were repairing damage to get power back to 46,000 homes and businesses on Sunday afternoon, with the Hunter region, Newcastle and the Central Coast the hardest hit areas.

About 180,000 customers have had their power restored after what Ausgrid described as "the worst disaster to ever hit the electricity network".

Gosford City Council is advising people stay out of Central Coast beaches and surrounding waterways due to concerns about leaking sewage.