2010 Western Australian storms

The 2010 Western Australian storms, also known as the "Storm of the Decade" were a series of storms that travelled over southwestern Western Australia on 21 and 22 March 2010. One of the more intense storm cells passed directly over the capital city of Perth between 3:30 pm and 5:00 pm on Monday 22 March 2010. As of 2024^[update], it is still the costliest natural disaster in Western Australian history, with the damage bill estimated at A$1.08 billion.^[1]

The storms brought extensive hail, strong winds and heavy rain, causing extensive damage to vehicles, property and trees, and flash flooding, as well as the first significant rainfall in Perth since 20 November 2009.^[2] The hail stones are the largest ever known to have occurred in Perth and were around 3–6 centimetres (1.2–2.4 in) in diameter,^[3] which caused extensive damage to property across the city,^[4] including schools, hospitals, universities and power infrastructure. Wind gusts were recorded at around 120 kilometres per hour (75 mph).^[2] At the peak, around 158,000 homes in Perth, Mandurah and Bunbury lost electric power.^[2][5] Fixed-line telephone services to thousands of homes were interrupted until the next day, and the storms led to an estimated $200 million worth of insurance claims within three days, with $70 million within the first 24 hours.^[6] It was identified as the most expensive natural disaster in Western Australia's history,^[7] and was declared a natural disaster by the Premier, Colin Barnett, allowing federal and state funds to be used for disaster relief.^[8][9]

The storm brought an end to a lengthy dry spell in Perth, with 40.2 millimetres (1.58 in) of rain falling at Mount Lawley – the fifth highest daily rainfall recorded for a March day in Perth. Over half of this fell in just 10 minutes.^[3] This was the first significant rainfall since 20 November 2009; only 0.2 millimetres (0.01 in) had fallen in the entire period. It was similar to storms which struck Melbourne on 6 March 2010.