​​hazard colour icon Storm.jpg

​​​​​​​​Honeycombs Beach, Wilyabrup, Western Australia. Image courtesy of Daniel Tuoma. 



What is a storm? 

A thunderstorm is sudden electrical discharges manifested by thunder and lightening. Thunderstorms are associated with convective clouds (cumulonimbus) an​d are, more often, accompanied by precipitation in the form of rain showers or hail. 

A severe thunderstorm produces one or more of the following:

  • ​​​​​Wind gusts of 90 km/h or more;
  • Hail with a diameter of 2cm or more; and​​​
  • Tornadoes: rapidly rotating columns of air that extend from the thunderstorm to the ground, most often in a ‘funnel’ shape. The term 'storm' is used to describe thunderstorms but also cold fronts and troughs which produce significant or severe weather.​

​​The term 'storm' is used to describe thunderstorms but also cold fronts and troughs which produce significant or severe weather.​


How do storms form? 

Thunderstorms can develop when warm, humid air near the ground surface is given an initial upward push from converging surface winds and rises rapidly i​​n an unstable atmosphere. If the atmosphere is particularly unstable and/or extra energy is drawn in from surrounding winds, thunderstorms can become severe.​


When do storms occur? 

Storms ​can occur any time of the year; but tend to follow two distinct patterns:
​​​1. A warm season storm: generally October to April
2. A cool season storm: generally May to September

Where do storms occur?

Storms can occur an​​ywhere across Western Australia but mostly impact coastal areas due to a loss of intensity as they move inland. The most common areas to be impacted are the southern and western coastal areas, particularly in a line from Geraldton to Esperance, due to large cold fronts in the winter months. Tornadoes can travel for several kilometres but are often localised and during a storm can form within the area of strong rotational winds.​


W​​hat are the impacts of a storm?

The impacts of storms can be significant and widespread. Specifically, impacts may be a result of the combination of hail, heavy rain, high winds and lightning. Potential impacts include:

  • ​​Injury and/or death to persons and animals
  • Damage/destruction of property
  • Damage to crops and harvest
  • Power failure
  • Commercial and industrial losses
  • Disruption and economic losses
  • Defoliation to local flora
  • Flood and hail damage​


Did you know? At any given moment, there are approximately 

2,000 thunderstorms in progress worldwide, 

producing approximately 6,000 lightning strikes every minute!​​

20​10 Perth storm 

Over two days in March 2010, a series of storms inflicted more than $1 billion worth of damage, primarily as a result of hail stones. The storm was the costliest event in Western Australian history and resulted in a large number of severely damaged vehicles and property. High rainfall also caused a mud slide near Kings Park and flash flooding throughout the city. A natural disaster was declared by the State.

Full Factsheet download​:


Storm Factsheet (pdf, ​390KB)​


Watch our Sto​​rm Hazard educational video (13.15 min)​: 



Further information about this hazard​​

More information about Storm can be found at: