Tropical cyclones get energy from very warm ocean water they sit above which needs to be at least 26.5C or higher to form. Photo: The Solomon Islands Meteorological Service
Explainer - The South Pacific tropical cyclone season is due to start in November and will run until the last day of April.
On average, there's nine each season, and tropical cyclones can straddle either end of the season, as seen last year with Lola in October.
But what actually is a tropical cyclone, and what do all the categories mean?
Here's everything you need to know.
What is a cyclone?
New Zealand's National Institute of Water and Atmospheric Research (NIWA) describes tropical cyclones as rotating storms, characterised by a low-pressure centre, strong winds, and thunderstorms that produce heavy rain.
NIWA meteorologist Ben Noll called them "vast heat engines".
Tropical cyclones get energy from very warm ocean water they sit above, which needs to be at least 26.5C or higher for them to be able to form. Water evaporates, and as the warm moist air rises, the developing tropical cyclone starts to spin.
"It becomes basically this engine of rising air," Noll said.
"It likes warm water, it likes winds that are relatively uniform through the atmospheric column, and it also likes moisture."
All tropical cyclones start as tropical lows, which can be also be destructive, bringing strong winds and rain.
The low becomes a tropical cyclone when the sustained wind speeds are higher than 63 km/h, but not all tropical lows form into cyclones.
What do the categories mean?
The strength of tropical cyclones is measured based on sustained wind speeds and categorized from one to five, with five being the most intense.
Category one tropical cyclones have sustained wind speeds from about 63 to 88 km/h, while category five having sustained winds surpassing 200 km/h.
Typically, the higher category the tropical cyclone is, the worse the impacts will be.
However, Noll said sometimes weaker tropical cyclones inflict more damage if they are slow moving or "stall out" over an island, so weak tropical cyclones should not be discounted.
What's the difference between tropical cyclones, hurricanes and typhoons?
They're all the same, but have different names depending on where they form.
In the Atlantic, they are called hurricanes; in the Western Pacific, they are called typhoons; and in the Southwest Pacific, toward Australia and Indian Ocean, they're called tropical cyclones.
What is the eye of a cyclone?
The eye is at the centre of the storm and has low atmospheric pressure. It typically has very light winds and clear skies. The winds are strongest just outside of the eye of the cyclone.
What does El Niño and La Niña mean?
El Niño and La Niña are opposite phases of the global climate cycle called the El Niño Southern Oscillation.
La Niña is the cooling phase, whereas El Niño is the warming phase of the waters in the eastern Pacific off the coast of South America.
Both have different effects on tropical cyclones in the South Pacific and where the majority likely to form.
Historically, El Niño seasons have come with a higher number of tropical cyclones in the region.
Cyclone Winston, the most intense tropical cyclone in the Southern Hemisphere on record, hit Fiji in February 2016 during an El Niño event.
The 1997/98 season was the most active tropical cyclone season in modern records for the Southwest Pacific and was also during an El Niño event.
In October last year, Cyclone Lola became the strongest off-season tropical cyclone measured in the Southern Hemisphere, with sustained winds of up to 215km/h.
Unusually for El Niño, last season only saw seven tropical cyclones form to the east of the tip of Cape York, Australia - two fewer than the long-term average.
This year, with a developing La Niña causing warmer ocean water to pile up in the western Pacific Ocean, the risk of cyclones to the west is greater than compared to the east.
What is climate change doing to cyclones in the South Pacific?
There may be slightly fewer but they could be stronger.
The long-term average number of cyclones in the South Pacific has dropped from 10 to nine in the last 30 years.
The water is getting warmer, so the maximum potential intensity that can be reached by cyclones that do form is now higher.
"A warming world doesn't necessarily produce more tropical cyclones, but it's still an active area of research," Noll said.
"With every passing season, it's a new data piece that gets factored into our thinking."
How are cyclones named?
A naming list is delivered annually through an organisation depending on where the cyclone is. For the South Pacific the naming list comes from Fiji's Metservice.
If a storm is so impactful, the name will not be reused, for example Winston in 2016 in the South Pacific and Hurricane Katrina in the Atlantic.
