On March 21/2 2010 severe hailstorms struck the central west , lower west , south west , central wheatbelt , great southern and the southern gascoyne areas of Western Australia. The cause of it was hot weather. Hot air at the bottom of the atmosphere causes water to evapurate and and then the moisture is cooled by the cold air at the top of the atmosphere and then rains back down and sometimes with hail. On March 21 storms formed in the Geraldton region , ending the city's fourth longest dry spell with 15 mm of rain falling in Geraldton. Badgingarra recieved 28 mm .of rain in 48 hours. Storms also devalopped in parts of the gascoyne where Cue got 80 to 100 mm of rain. Northerly winds caused the thunderstorms to head south on the 22nd of March. A severe thunderstorm warning was issued for central west , south west and central wheatbelt at 9:45 am and amended at 2:30 pm to indicate the threat to Perth. As predicted, thunderstorms began at Jurien bay around 2 pm which dumped 36 mm of rain. Thunderstorms dropped the temprature by 5 degrees celcius at Gingin and dumped 18 mm of rain. Perth was next in line for storms and had the most severe storm out of all, dumping 126 mm of rain , hailstones of up to 6 cm across and brought a gust up to 96 to 128 KPH. The storm struck about 3:30 pm AWST. The hailstones reported was the largest ever recorded in Perth history. A week after the thunderstorm outbreak , the damage reached $650 million. The total damage was $1.08 billion which was the most expensive damage in Western Australian history , however no one died. In Kingspark over 100 people were evacuated when a mudslide struck due to heavy rain. Schools did not open until 23rd of March due to extensive storm damage.