Heavy bursts of rain and gusty south-easterly winds are expected throughout the morning on Friday, before the rain eases to showers in the afternoon and into the weekend.
Weatherzone meteorologist Tristan Meyers said the Sydney basin was forecast to reach a top of 22 degrees on Friday, a far cry from the scorching 40-degree heat Sydneysiders endured before storms swept through about 2pm on Thursday.
The wind was so ferocious that a man was killed when a large tree crashed onto a car on the Great Western Highway at Emu Plains, while multiple buildings were destroyed. A woman who was in the car was flown to Westmead Hospital with serious injuries.
"There won't be a repeat of yesterday. We will have cool rain throughout the day, easing to showers in the afternoon," Mr Meyers said.
Up to five millimetres of rain an hour was expected to fall during the morning commute, with heavy bursts at times decreasing visibility on the roads, Mr Myers said, while winds could reach up to 35km/h in the morning.
The State Emergency Service (SES) had received 1842 calls for assistance by Friday morning, predominantly from people in Mount Druitt, Blacktown, Bankstown, Penrith, Sutherland and Wyong.
Most of the damage was caused by trees and branches falling onto homes and power lines, while many calls were received for leaking roofs, an SES spokesperson said.
The Transport Management Centre (TMC) urged motorists to be cautious in some parts of Sydney and Newcastle, where traffic lights remained blacked out. The main areas affected were Liverpool, Blacktown, Penrith, the Hills district, and parts of Sutherland and Newcastle.
"All resources are working to restore signals; however, due to the high number of traffic signals impacted by severe storms, there is no forecast available as to when all signals will be fully restored," the TMC said in a statement.
At the height of the storms, power was cut to 40,000 homes in Sydney, the Central Coast and the Hunter on Thursday.
Ausgrid said about 4000 of its customers in Sydney, 3000 on the Central Coast and 7000 in the Hunter remained without power on Friday morning. The main areas in Sydney were Brooklyn, East Hills, Milperra and smaller pockets in Sydney's south. On the Central Coast, the main areas include Berkeley Vale, Narara and Niagara Park.
An Ausgrid spokesperson said additional crews had been brought in on Friday to repair the damage.
Meantime, Endeavour Energy said about 10,200 of its customers were still without power on Friday morning, mainly in Mount Druitt, Bargo, Liverpool and Cabramatta.
"As the storm damage was widespread, we expect the repair work to continue into this evening and possibly into the weekend," Endeavour Energy said in a statement.
"This means some customers may still be without power tonight. Endeavour Energy understands the inconvenience this causes, and would like to thank affected customers for their patience as we work to safely restore their power supply."
Mr Meyers said showers and strong winds were forecast to continue on Saturday, with the mercury expected to peak at 23 degrees in Sydney.
"Those winds will make it feel quite brisk as well at times, taking 2 degrees off what the temperature may actually suggest," he said.
"Showers will continue to break up over Sunday, with more and more sunny breaks."
A top of 24 degrees is forecast in Sydney on Sunday.