Australian Severe Thunderstorm Guide
Understanding severe storms, lightning, and supercell threats
Overview
Australia experiences thousands of thunderstorms annually, with some regions averaging over 80 thunderstorm days per year. Severe thunderstorms can produce destructive winds exceeding 125 km/h, giant hail larger than golf balls, heavy rainfall causing flash flooding, and dangerous lightning.
The Bureau of Meteorology issues Severe Thunderstorm Warnings when storms are expected to produce damaging winds, large hail (2cm+), heavy rainfall, or tornadoes. Supercell thunderstorms are particularly dangerous, capable of producing all severe weather types simultaneously.
The Sydney hailstorm of 1999 remains Australia's most expensive natural disaster, causing $5.6 billion in damage (adjusted). More recently, the 2020 Canberra hailstorm and numerous Brisbane supercells have caused billions in damage.
Causes & Contributing Factors
- Strong atmospheric instability (warm air below cold air)
- High moisture content in lower atmosphere
- A trigger mechanism (cold fronts, troughs, sea breezes)
- Wind shear for supercell development
- Convergence zones where air masses meet
- Topographic lifting over mountains
- Afternoon heating during summer months
Safety Tips
Shelter Immediately
When thunder roars, go indoors. Seek substantial shelter in a building or hard-topped vehicle. Avoid sheltering under trees or in small structures.
Stay Away from Windows
Large hail can shatter windows. Move to an interior room away from windows during severe storms. Close curtains to contain broken glass.
Unplug Electronics
Lightning can travel through electrical wiring. Unplug sensitive electronics and avoid using corded phones or appliances during storms.
Protect Vehicles from Hail
If possible, move vehicles under cover before storms arrive. A carport or covered parking can prevent thousands of dollars in hail damage.
Avoid Water During Lightning
Get out of pools, lakes, and beaches immediately when storms approach. Lightning can travel through water and plumbing.
30/30 Lightning Rule
If the time between lightning and thunder is 30 seconds or less, seek shelter. Wait 30 minutes after the last thunder before going outside.
Regional Information
Southeast Queensland
- Australia's most severe storm region
- Supercells regularly produce giant hail (5cm+)
- Sea breeze convergence creates afternoon storms
- 2014 Brisbane supercell caused $1.4 billion damage
Frequently Asked Questions
Approaching Storm Signs
- Severe Thunderstorm Warning issued by BOM
- Large, dark, towering clouds (cumulonimbus)
- Green tinge to sky (can indicate hail)
- Sudden temperature drop
- Increasing wind and change in wind direction
- Large hail falling nearby
- Continuous thunder and lightning
Seasonal Risk Pattern
Peak severe storm season. Supercells most common. Highest hail and damaging wind risk.
Storms continue into March/April. Can still produce severe events. Season winding down.
Few thunderstorms in southern Australia. Northern monsoon provides storms in Top End.
Storm season begins. First supercells of season often catch people off guard. Increasing activity.