On this day in history: Sydney supercell hailstorm

Aggregate hailstone (Photo: National Oceanic and Atmospheric Administration)

ON THE EVENING OF 14 April 1999 hailstones began to pelt down on Sydney homes at over 200km/h, forcing the residents of our biggest city inside.

The NSW Fire Brigades Sydney Communication Centre was quickly inundated with calls as destroyed roofs, flooding and electrical fires piled up. In five hours, 2000 emergency calls flooded in — one every 10 seconds — and the Government promptly declared a state of emergency. (Scroll down for video.)

Sydney hail storm most expensive in history

Caught off-guard in a period of normally mild weather, the Bureau of Meteorology didn’t have specialist staff on duty when the supercell storm struck and defied predictions by moving over the city centre, rather than heading out to sea as expected.

After it blew over the storm the damage included 20,000 buildings, 40,000 vehicles and 25 aircraft. The $1.7 billion cost was more than the total cost of Cyclone Tracy, which hit Darwin in 1974, and even the cost of the Ash Wednesday bushfires in 1983. It is, to date, the most expensive natural disaster in Australian history. 

Hail a natural hazard insurance nightmare

Hail is a recurrent problem in Sydney. On average, stones 4 cm in diameter fall once a year and stones 6 cm in diameter — hail that can break new concrete — once every two years. Huge, cricket-ball-sized hailstones (8 cm in diameter) fall every 5-10 years. So, although we tend to fear the destructive power of the bushfire, between 1968 and 2005 hail was responsible for over one-third of the the country's total natural hazard insurance losses. Moreover, more than 75% of these were in NSW.

Professor Alan Jeary from the School of Engineering at University of Western Sydney says Sydney houses aren’t built sturdily enough to withstand these ice missiles, and that tile and slate roofs would benefit from a rethink. And sooner is probably better, because modelling work by academics suggests that the return period for a storm like the 1999 supercell storm is 25-30 years.



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Australia’s first state is home to some of the country’s most beautiful treasures. The Great Dividing Range, like a gigantic backbone, supports snowfields to the south and majestic rainforests to the north, and separates the red sandhills from the picturesque surf beaches of the Pacific.