Hailstorms can cause substantial damage to property. The April 1999 hailstorm in Sydney caused $1.7 billion (2003 dollars) in insured losses, making it one of the Australia’s most costly natural disasters. Most areas on the mainland south of the Tropic of Capricorn are at risk from hail. Damaging hail is rare in the tropics and in Tasmania. Hail risk is a function of the intensity and frequency of hail, where intensity is represented by hail stone size and frequency is the number of storms per unit area per year5.
Analysis was conducted using historical information on the frequency and intensity of past hailstorm events, Risk Frontiers’ HailAUS model and gridded climate re-analysis data.
The five-point scale below outlines the hailstorm risk ratings used in this report. The scale describes the probability of hail occurrence greater than 2 cm in diameter.
- Very High (5) – For regions that experience very frequent potentially damaging hailstorms
- High (4) – For regions that experience frequent potentially damaging hailstorms
- Medium (3) – For regions where potentially damaging hail is possible
- Low (2) – For regions were damaging hail is rare
- Negligible (1) – For regions were damaging hail is very rare or has never been recorded