Three tropical cyclones are churning in the South Pacific, an occurrence that scientists say is unusual.

Tropical cyclones Rae, Seru and Alfred are all spinning as the region’s cyclone season, which starts in November and ends in April, reaches its peak.

“Certainly it is a very busy period for the South Pacific and three tropical cyclones is a lot to happen at once, but not unprecedented,” said Brian Tang, an atmospheric science professor at University at Albany.

The last time three such storms occurred in the South Pacific was January 2021 when Lucas, Ana and Bina were churning simultaneously, Tang said.

Rae formed on Friday north of Fiji and brought whipping winds and heavy rain that damaged fruit trees, according to local reports.

Alfred developed in the Coral Sea on Monday and is expected to bring flooding rains to Queensland, Australia, this weekend.

Seru became a cyclone on Tuesday and is expected to track near the island nation of Vanuatu but remain offshore.

Gabriel Vecchi, a climate scientist at Princeton University, noted evidence of what’s called a Madden–Julian Oscillation — a fluctuation in the atmosphere that results in a blob of rising air and rainfall that circles the globe and lasts for 30 days or longer. He said it seems to be tracking over the south-west Pacific in a way that could enhance cyclone activity.

“The atmosphere is chaotic. There’s a lot of natural fluctuation in it … we need to be open to the possibility that factors that are beyond our ability to predict might have led to these three cyclones at the same time,” said Vecchi.

Tropical storms are called cyclones when they happen in the south-west Pacific and hurricanes when they form in the north Atlantic, but they are essentially the same weather event.