Green Cross Australia

This is a Green Cross Australia project

Empowering a resilient Australia

Weather Events Explained

Learn about different elements of weather, Australia's climate and definitions for terms used throughout the website.



The ACT is nicknamed “bush capital” for a reason – we have encouraged the bush to grow within our city, which means our suburbs and rural areas are exposed to bushfires. There are a number of factors that affect bushfires. Learn more...


Climate vs weather

Climate change means a change in the average pattern of weather over a long period of time. To understand climate change, first you must understand the difference between weather and climate. Learn more...



The Canberra region has experienced an average of one earthquake per year for the past 50 years; and for most residents this information would come as a surprise. Frequency of occurrence of earthquakes within 20 km of Canberra GPO Seventy-two earthquakes occurred within 20 km of the GPO in the 36 years prior to the end of 1995, and during this period yearly numbers varied between zero and nine with a mean number of 2.0. Learn more...


Flash floods

Flash floods can occur almost anywhere there is a relatively short intense burst of rainfall such as during a thunderstorm. As a result of these events the drainage system has insufficient capacity or time to cope with the downpour. Although flash floods are generally localised, they pose a significant threat because of their unpredictability and normally short duration. Learn more... 


A simple definition of flooding is water where it is not wanted. The supercell thunderstorm that resulted in the tragic 1971 Woden Flood shows how deadly floods can be. Over recent decades measures have been taken to protect Canberra from historical flooding impacts, but torrential rainfall can happen anywhere in the ACT. On 26 January 1971, up to to 100 mm was recorded in one hour by private rain gauges in the suburb of Farrer and Torrens. Learn more...



During a ‘heatwave’ temperatures are above average for several sequential days and it remains hot overnight. Heatwaves have caused more deaths than bushfires in Australia, and cause losses to crops, livestock and infrastructure. Learn more... 


According to Emergency Management Australia and the Bureau of Meteorology:

Hailstones can form in a thunderstorm with a strong updraught when frozen raindrops, suspended in the updraught, grow rapidly by sweeping up small cloud droplets which freeze on contact. Hailstones larger than cricket balls have been recorded in Australia. Learn more... 


Lightning and thunder

According to the According to Emergency Management Australia and the Bureau of Meteorology: 

Lightning is the discharge produced when voltage differences between ground and atmospheric electrical charge are large enough (several hundred million volts) to overcome the insulating effect of the air. Strokes can occur within the cloud, between clouds, or between clouds and the ground. Thunder is the sound produced by the explosive expansion of air heated by the lightning stroke to temperatures as high as 30,000°C. Learn more... 


105 people have been killed by landslide events since 1842 in 100 recorded landslide events (National Landslide Database, 2007). Many of these events resulted from natural phenomenon, though half of those causing death and injury can be attributed to human activity. Learn more...  


Severe storms

Storms can happen anywhere, but they are more common in the ACT from September to end of February. Severe storms are more common than any other natural hazard and are responsible for more damages measured by insurance costs than bushfires, floods or cyclones.

A severe thunderstorm is defined by the Bureau of Meteorology as one which produces; hail, diameter of 2 cm or more ($2 coin size); or wind gusts of 90 km/h or greater; or flash floods; or tornadoes, or any combination of these.  Learn more... 



Many people believe that tornados do not occur in Australia; this is not true, they do and have caused numerous deaths. Most thunderstorms do not reach the level of intensity needed to produce these dangerous phenomena, but they all produce lightning which can cause death, injury and damage. Tornados can and do occur in the ACT. Learn more...