Man almost loses arm after wild storm brought down tree in NSW

A man is battling to save his right arm after a tree came down on his home on the NSW mid-north coast during yesterday's dangerous storm.

A major clean-up is underway across southern Sydney, parts of the NSW coast and the ACT after wild weather brought down trees, ripped roofs off buildings and trapped people.

In Harrington, near Taree, a tree believed to be struck by lightning fell came crashing down on a house at around 6pm yesterday.

The home is owned by local Philip Shoesmith, who was inside at the time.

Family friend Teena Wobcke told Nine.com.au that Mr Shoesmith was airlifted to the John Hunter in Newcastle where doctors were battling to save his right arm.

"I just spoke to his sister, he got out of surgery at 2am this morning. His right arm was absolutely smashed to smithereens with compound fractures. His left leg was lacerated, and he could have major never damage. It's just horrific," Ms Wobcke said.

Ms Wobcke said concerns about the same tree had been raised to the local Mid-Coast Council last year after it was struck by lightning for the first time.

A number of strong storm cells made their way through the state, hitting Canberra and then stretching from the NSW mid-north coast down to the Victorian border.

Little Blessings Early Learning Centre in Carringbah had the roof ripped off it, while a tree crushed a vehicle in the same suburb.

Canberra storm deemed 'catastrophic'

The Insurance Council of Australia has declared the damage caused by a huge storm that dropped golf-sized hailstones on the Nation's capital a "catastrophe".

Insurers have received more than 29,000 claims, the council said in a statement.

Of these, 56 per cent are from the ACT, 34 per cent from Victoria and 10 per cent from NSW.

ICA Head of Risk and Operations Karl Sullivan said insurers would prioritise claims from hail-affected areas and were already advising customers about assessments and repairs.

Thousands more claims are expected to be lodged this week, as people surveyed the damage.

"Property owners should contact their insurer before commissioning any repairs to their homes or business to ensure these works are paid for under their policy," he said.

CSIRO experiments 'destroyed'

The CSIRO in Canberra said 65 of its glasshouses were damaged in the destructive hailstorm yesterday.

Photos show glass panels on top of the buildings completely shattered by the huge hail stones.

The experiments that were destroyed were aimed at improving crop sustainability.

"We're very fortunate that none of our staff were hurt," it wrote on Twitter.