On December 20, 2018, the NSW coast was battered with hail that would easily match a mean cricket ball in a fair fight. Severe storms were reported from the Central Coast down to Kiama in the south, with icy stones up to 8cm in diameter accosting areas like Berowra on the upper North Shore and pelting out to Western Suburbs like Oran Park, Harrington Park and Casula.

Just one day after hailstorms pummelled Sydney and the central coast, it is already the most expensive catastrophe for insurance companies this year.

In Sydney, the hail onslaught started in the west at around 5pm and was ravaging the inner city suburbs within an hour. Some in Redfern put the buckets of sky ice to good use

But the outcome for most was much less merry

Tens of thousands of homes from the Blue Mountains, through Sydney’s Western Suburbs and up to the Hawkesbury were left without power, and 62 flights out of Sydney Airport were cancelled, with 90-minute delays in the domestic terminal and three-hour set backs for international travellers.

Sydney homes saw major roof damage, there were stoppages across the Sydney train network and smashed car windscreens were all the rage.

Surfers at Bondi Beach had few options for shelter, and while many made a dash for the shore, some stuck it out in the water and used their boards for cover.

At Berowra, on the upper North Shore, there were reports of hail about 8 centimetres wide, while Cabramatta in the south-west and parts of Surry Hills received hail about half that size.

A State Emergency Service spokesperson said Berowra was one of the worst-hit areas, with “almost every second home” needing assistance.

“Giant hailstones, which is hail greater than 5 centimetres, are quite specifically driven in supercell thunderstorms. We do get them quite regularly over summer through NSW, but these storm cells redeveloped quite intensely over Sydney specifically,” meteorologist Jordan Notara said.

The severe hailstorm was accompanied by strong winds of up to 140km/h (87 mph) and somes eerie and rare greenish-blue clouds.

A green sky may be a sign of an impending tornado or huge hail (in this case it was true!), but the exact cause of this is still subject to debate today.

By 7.30pm, the Insurance Council of Australia had declared the deluge a catastrophe, with damage costs estimated to be in the tens of millions. The full impact of the storm will become clear in the coming days, as more insurance claims are added to the 15,000 already logged.