So what does this mean, and just how destructive will it get?
Here is everything we know about the rating system.
How are cyclones categorised
A numerical scale from one to five is used to rate the destructiveness of cyclones, with five being the strongest.
The intensity ratings are based on maximum wind gusts associated with the cyclone.
These usually occur around the eye of the storm.
What is the strongest cyclone category
Category Five is the strongest cyclone category.
How strong is a category five cyclone
Andrea Pearce, senior meteorologist at the Bureau of Meterology (BoM), said a category five cyclone has “estimated gusts of 280 km/hr and above”.
Isla is expected to make landfall later tonight with wind gusts in excess of 280 km/hr.
“The very destructive core of Ilsa, with extreme gusts up to 285 km/hr is expected to impact the area,” BoM said.
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Category five cyclones history in Australia
Cyclone Darian, which formed in December well off Australia’s mainland was the last category five cyclone to fall in the country’s area of responsibility.
However, Cyclone Lawrence in 2009 was the last category five to make landfall.
It hit Eighty Mile Beach in WA on the December 21.
“Mandora recorded a wind gust to 211 km/h during landfall, but it likely produced gusts of 285km/h at its peak,” Weatherzone said.
Worst cyclones in Australia history
The deadliest tropical cyclone in Australian history was Cyclone Mahina, another Category Five.
It struck Bathurst Bay in Far North Queensland on March 5, 1899 – it killed an estimated 410 people when it scuttled a sheltering pearling fleet.
Cyclone Yasi, which hit Far North Queensland coast in February 2011, was one of the largest storms in recent history.
The slow-moving Category Five system resulted in thousands being evacuated from Cairns.
Banana and sugar cane crops where flattened by the 285km/hr wind gusts.
It was estimated to cause $3.6 billion in damage – the most costly cyclone in Australia to date.
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