Thunderstorms are a weather phenomenon that while seeming innocuous can cause substantial insured losses. Between 1969 and 1999 insurance related claims resulting from thunderstorms (including wind, hail and flash flood damage) amount to approximately $5B9. Lightning accompanying thunderstorms have caused 650 registered fatalities in Australia between 1803-199210.
Analysis was conducted using Bureau of Meteorology data for average annual thunder days and lightning ground flash density.
The five-point scale below outlines the thunder risk ratings used in this report. The scale describes the probability of thunder occurrence on an average annual number of days at that point location.
- Very High (5) – For regions that experience more than 51 days of thunder on average per year
- High (4) – For regions that experience more than 30 and less than or equal to 50 days of thunder on average per year
- Medium (3) – For regions that experience more than 20 and less than or equal to 30 days of thunder on average per year
- Low (2) – For regions that experience more than 10 and less than or equal to 20 days of thunder on average per year
- Negligible (1) – For regions that experience less than or equal to 10 days of thunder on average per year
The five-point scale below outlines the lightning risk ratings used in this report. The scale describes the probability of cloud to ground lightning flash density per square kilometer on an average annual number of days at that point location.
- Very High (5) – For regions that experience more than 6 flashes of lightning per square km on average per year
- High (4) – For regions that experience more than 4 and less than or equal to 6 flashes of lightning per square km on average per year
- Medium (3) – For regions that experience more than 2 and less than or equal to 4 flashes of lightning per square km on average per year
- Low (2) – For regions that experience more than 1 and less than or equal to 2 flashes of lightning per square km on average per year
- Negligible (1) – For regions that experience less than or equal to 1 flashes of lightning per square km on average per year