On February 6, Tropical Cyclone (TC) Freddy was named off the West Australian coast before strengthening rapidly and heading west over open waters.
Thirty-six days later it was still going, becoming one of the most energetic and long-lasting cyclones in history.
"We never thought it was going to turn into the event that it has, back in early February," the Bureau of Meteorology's Craig Earl-Spurr said.
The deadly storm system traversed the entire Indian Ocean, travelling more than 8,000 kilometres and devastating Southern Africa as it barrelled over Malawi, Madagascar and Mozambique.
Freddy became one of the most energetic storms on record by measure of its wind strength over its lifetime — known as accumulated cyclone energy.
It rapidly intensified several times, and could end up the longest-lasting cyclone in recorded history.
This is under assessment by the World Meteorological Organization, with the current record of 31 days set by Hurricane John in 1994.
So what gave it so much stamina and strength?
Fuelled by westerly track
Regional Specialised Meteorological Centre La Réunion head of operations Sébastien Langlade said one of the key reasons it maintained its strength was its westerly track, which helped keep TC Freddy over warmer waters.
"What happens usually is the system tracks toward [the south] where the waters are not warm enough and where the atmospheric conditions become hostile," he said.
"But this was not the case this time.
"The system was embedded within an environment that prevented him from going too far to the south and losing the warm waters."
Dr Langlade said this had only happened twice before in the Indian Ocean.
Intense TC Leon-Eline made its way from north-west Australia to southern Africa during February, 2000, while Intense TC Hudah later that year also traversed the entire Indian Ocean.
Like Freddy, these two cyclones occurred in a La Niña year.
A possible La Niña influence
Dr Langlade said La Niña was known to favour the track of tropical cyclones oriented toward the west.
"And even though La Niña is off now, it was the case during the last month and the two previous tropical cyclone seasons," he said.
"And we observed several westward tracks [of cyclones].
"But the example of Freddy is an extreme one."
Dr Langlade said it was also possible another tropical cyclone, Dingani, which was in the southern Indian Ocean at the time, "indirectly" influenced Freddy's path to the west.
"It's possible that we had an indirect influence of Dingani that created a strengthening of the sub-tropical ridge to the east of Dingani and kept Freddy on a westward track all the way through the Indian Ocean," he said.
But like many other aspects of Freddy, he said, it would need further research to know for sure.
Prolonged by 'radical' looping path
Dr Langlade said the erratic path of TC Freddy when it reached the Mozambique channel also extended its life considerably.
It was during this period of the cyclone that it was most destructive, barrelling over south-eastern Africa twice.
Hundreds of people were killed as it made impact, with reports whole villages were washed away without a trace.
On February 21 the system made landfall over Madagascar and continued westward, striking Mozambique on February 24.
It then looped back into the Mozambique channel and redeveloped.
Freddy then completed a third U-turn toward the Mozambique coast, where it struck for a second time.
"This part of the track is something that is quite unusual," Dr Langlade said.
"What we have seen is that the steering flow, which drives the track of the cyclone, shift radically over a couple of days."
Dr Langlade said the rapid change in direction extended the duration of the cyclone's life by about 10 days.
"It was like Freddy and Freddy 2.0," he said
"And, unfortunately, we found a case of a rare and extreme event that affected the most vulnerable people on the planet."
Climate change links unclear
Dr Langlade said the length and strength of TC Freddy was truly "remarkable" and warranted further research, especially in regards to any links to climate change.
"There is a question of how this kind of motion could be more frequent in a warmer climate in the future, and if it's linked to climate change or not," he said.
CSIRO climate scientist Kathleen McInnes authored the latest IPCC Special Report on Oceans and Cryosphere, which looked into the way tropical cyclones could be attributed to climate change.
She said the cyclone's strength was consistent with trends of climate change.
"In general, there is a consensus that there will be fewer cyclones but once they've formed they can potentially be stronger," Dr McInnes said.
But Dr McInnes said it was less clear how climate change might have played a role in TC Freddy's longevity.
"It's a long track and I don't believe it was a fast moving cyclone, so that is kind of consistent with some early findings that have been [made] that cyclones may be slower under climate change," she said.
"But I think it's a bit too early to say anything."
Dr McInnes said in the months to years ahead there would be "a lot of research" on TC Freddy and its various attributes and characteristics in the context of the changing climate and changing ocean conditions.
