How severe are hailstorms?


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How severe are hailstorms?

Damage from hailstorms can have a devastating impact on a family's home and financial situation. These storms, which can happen at any time of the year but are more common from September to Marchi, sometime produce large hailstones that can leave a property in need of extensive repair. Hail was responsible for more than a third of the nation's total natural hazard insurance losses between 1968 and 2005ii.

Hailstorms are common in Australia, particularly in New South Wales and the Australian Capital Territory.

Hailstorms: a common occurrence in Australia

Storms that produce large hailstones (greater than 2cm in diameter) are called severe convective storms and they occur often in Australia, most commonly in New South Wales and the Australian Capital Territoryiii.

One particular hailstorm in recent history was memorable for the damage done. On 14th April 1999, cricket-ball sized hailstones - the largest hailstone officially measured was 9cm in diameteriv - pelted the city of Sydney at speeds of up to 200km/hr. The storm, which took residents and meteorologists by surprise, was so severe that the State Government declared a state of emergencyii. The remarkable hailstorm caused damage to 20,000 building roofs and 40,000 vehiclesii, affected around 130,000 people and resulted in an estimated $1.7 billion in damageiv. The hailstorm was one of the most expensive natural disasters in Australia's historyv.

But they're not just a problem for those in NSW and the ACT. In 2005, a hailstorm that hit Queensland's Gold Coast racked up a bill of $60 million in damagesvi. More recently, in 2010, Perth experienced a catastrophic storm (torrential rain, hail and flooding) that resulted in $1.05 billion in damagesvii.

Impact of a hailstorm

The possibility and extent of damage to property by hailstones depends on a number of factorsv:

  1. Frequency and intensity of the hailstorm
  2. The size of the hailstones and the velocity of their impact
  3. Wind speed
  4. The vulnerability and exposure of buildings to the hailstorm

The toughness of a home's roofing material will also be significant in the likelihood of damage - poor quality material and old roofs are most susceptible to hailstone damage. But any part of the building facing the sky is vulnerable to damage by hailstones.

Older roofs are more susceptible to hailstone damage.

A report compiled by the Australian Building Codes Board in 2010 identified that the major structural damage caused by hailstones are: permanent indentation in metal roofing, damage to glass, cracked roof tilingviii and the build-up of hailstones in a gutter system. All these can cause primary structural damage to the object that’s been struck and secondary damage if the inside of the home is exposed to the elementsviii.

Protecting your home

Protecting your home is all about being prepared. To minimise damage in the event of a hailstorm, ensure that youix, x:

Of course, these must be done prior to the start of a storm. Another option is to reinforce your home with hail resistant roofing materials. Despite the frequency of storms and the extensive damage that can occur from a hailstorm, Australian building codes do not currently require roofs to be resilient to hail damagex.

Protecting your home with adequate levels of building and contents cover is one part of preparing your home against financial loss from hailstone damage. At Allianz, our SureCover home insurance policy is designed to protect your home and contents from loss or damage caused by one or more of the insured events, including fire or smoke, storm (hail included), theft, rainwater or run-off to name just a few. Get an online quote from Allianz today in just 2 minutes, or call us on 13 1000 to arrange a new home insurance policy.


i Bureau of Meteorology, Facts on Hail in NSW, http://www.bom.gov.au/nsw/sevwx/hailfact.shtml

ii Australian Geographic, 2010, On this day in history: Sydney supercell hailstorm, http://www.australiangeographic.com.au/journal/on-this-day-in-history-sydney-supercell-hailstorm.htm

iii RMS Special Report, 2009, The 1999 Sydney Hailstorm: 10-year Retrospective, http://www.rms.com/publications/1999_sydney_hailstorm.pdf, p.2

iv RMS Special Report, 2009, The 1999 Sydney Hailstorm: 10-year Retrospective, http://www.rms.com/publications/1999_sydney_hailstorm.pdf, p.1

v Schuster, S. & R. Blong, 2004, Hailstorms and the Estimation of their Impact on Residential Buildings Using Radar, Sixth International Symposium on Hydrological Applications of Weather Radar, http://www.cawcr.gov.au/bmrc/basic/old_events/hawr6/poster_session_1/SCHUSTER_hailstorms.pdf, p.1

vi Australian Government, Emergency Management Australia, 2007, Storm and Water Damage Operations (3rd edition), http://www.em.gov.au/Documents/Manual30-StormandWaterDamageOperations.pdf, p.v

vii Insurance Council of Australia, 2012, Historical Disaster Statistics, http://www.insurancecouncil.com.au/industry-statistics-data/disaster-statistics/historical-disaster-statistics

viii Australian Building Codes Board, 2010, An Investigation of Possible Building Code of Australia (BCA) Adaptation Measures for Climate Change, http://www.abcb.gov.au/en/~/media/Files/Download%20Documents/Consultation/2010-12_Investigation_of_Possible_BCA_Adaptation_Measures_for_Climate_Change_Final.pdf, p.68-9

ix Australian Government, Emergency Management Australia, 2007, Storm and Water Damage Operations (3rd edition), http://www.em.gov.au/Documents/Manual30-StormandWaterDamageOperations.pdf, p.3

x Insurance Council of Australia, 2010, Consumer tips: Increasing Resilience to the Impacts of Extreme Weather - Property Durability to Hail, http://www.insurancecouncil.com.au/assets/files/property%20durability%20to%20hail.pdf