The Insurance Council of Australia (ICA) has declared the incident a "catastrophe".
The bill for the catastrophic hailstorm that struck Sydney and other parts of NSW is expected to be more than $20 million with 15,000 people lodging claims so far.
The SES has received over 3600 calls since 3pm yesterday and has responded to over 2100 individual requests for assistance.
The destruction spread far and wide across NSW, with the worst affected areas having been identified today as Berowra Heights, Liverpool, Lithgow and as well as Gosford on the central coast.
Tamworth was also hit with a super intense storm with cyclonic winds. The SES described the damage as widespread, stressing that cleanup efforts would be difficult this close to Christmas.
Tennis ball-sized hail smashed homes and cars in Sydney's west while golf ball-sized stones battered the city's inner suburbs an hour later, at 6pm. The Insurance Council of Australia declared the incident a catastrophe at 7.30pm and activated support measures for affected residents.
Thousands without power
Powerful winds were recorded up to 140 km/h, downing trees and telegraph poles.
As powerlines are still down, around 50,000 homes are still without power according to the SES.
Around 200 electrical hazards were left in the wake of the storm after power lines came down.
Tennis ball-sized hail smashed homes and cars in Sydney's west while smaller, golf ball-sized stones battered the city's inner suburbs an hour later at 6pm. Social media was awash with photos of massive hailstones on the city's fringes and videos which showed crowds huddled under awnings as city roads were covered by ice.
The Insurance Council of Australia (ICA) declared the incident a "catastrophe" by 7.30pm.
Reports of "extensive damage" to cars and homes had been received from Sydney's west to Bondi Beach, ICA spokesman Campbell Fuller told the Daily Telegraph.
"There are likely to be tens of millions of dollars in claims, if not more," he said.
"They have to be huge events with widespread impacts on the community.
"An insurance catastrophe is declared by the Insurance Council when the Insurance Council believes an extraordinary response is required to the extent of the damage.
"We only declare catastrophes several times a year."
Windshields had been smashed, roofs damaged and both cars and homes impacted by flash flooding.
Heavy rain and hailstones the size of fists pelted down as multiple storm fronts converged on the regions.
The SES currently has around 500 crew members on the ground responding to calls.
"The main issue for the SES is they've seen giant hail up to 8 cm in diameter. We've seen a lot of roof damage, broken skylights, broken windows," said Phil Schafer, the NSW SES Media Officer.
"Therefore our crews will be doing a lot of tarping of roofs to prevent furthers leak to to get into homes."
Grafton, Hornsby, Berowra Heights, Newcastle, Gosford, Wollongong, Nowra, Batemans Bay, Tamworth and Moree were also in the firing line. The SES has set up a mobile command to assist their cleanup efforts in Berowra Heights in the Hawesbury area outside Sydney.
The Bureau of Meteorology has yesterday issued a severe thunderstorm warning for heavy rainfall, damaging and locally destructive winds and "large … giant hailstones" for large parts of the state including Sydney, Newcastle, the Hunter Valley, Wollongong and Dubbo.
