Cyclones, called hurricanes or typhoons in other parts of the world, can sometimes affect New South Wales, with the coastal areas in northern parts of the state being most at risk. Although, the impacts of cyclones can extend to the south and inland areas of NSW.
Cyclones form over warm tropical waters where the sea's surface temperature is above 26° C. A cyclone forms in an area of low pressure, which draws in surrounding winds. As the Earth rotates, it creates forces that cause the winds to swirl around the low pressure. This helps the cyclone start to spin. They are typically hundreds of kilometres in diameter and can last for many days, bringing strong winds, heavy rain, flooding and storm surges that can cause major damage.
Intense low-pressure systems known as East Coast Lows and Low-Pressure Troughs are more common in NSW. They generally develop close to the coast and can intensify dramatically. They can produce gale to storm-force winds, heavy rainfall, and in some cases very high seas and storm surges.
Due to their relative fast development and short life cycle, warnings issued for East Coast Lows will usually have less lead time. The Bureau of Meteorology forecasts may also mention localised heavy rainfall, strong winds and dangerous surf, in the lead-up to an East Coast Low or Low-Pressure Trough.