The 1999 Sydney hailstorm was the costliest natural disaster in Australian insurance history, causing extensive damage along the east coast of New South Wales. The storm developed south of Sydney on the afternoon of Wednesday, 14 April 1999 and struck the city's eastern suburbs, including the central business district, later that evening.The storm dropped an estimated 500,000 tonnes of hailstones in its path. Insured damages caused by the storm were over A$1.7 billion, with the total damage bill (including uninsured damages) estimated to be around A$2.3 billion. It was the costliest in Australian history in insured damages, surpassing the A$1.1 billion in insured damages caused by the 1989 Newcastle earthquake. Lightning also claimed one life during the storm, and the event caused approximately 50 injuries.The storm was classified as a supercell following further analysis of its erratic nature and extreme attributes. During the event, the Bureau of Meteorology was constantly surprised by the frequent changes in direction, as well as the severity of the hail and the duration of the storm. The event was also surprising as neither the time of year, time of day, nor the general meteorological conditions in the region were seen as conducive for extreme storm cell formation.