From BBC
Hurricanes Helene and Milton – which have devastated parts of the south-east United States – have bookended an exceptionally busy period of tropical storms.
In less than two weeks, five hurricanes formed, which is not far off what the Atlantic would typically get in an entire year.
The storms were powerful, gaining strength with rapid speed.
Yet in early September, when hurricane activity is normally at its peak, there were peculiarly few storms.
So, how unusual has this hurricane season been – and what is behind it?
The season started ominously. On 2 July, Hurricane Beryl became the earliest category five hurricane to form in the Atlantic on records going back to 1920.
Just a few weeks earlier in May, US scientists had warned the 2024 season from June to November could be “extraordinary”.
It was thought that exceptionally warm Atlantic temperatures – combined with a shift in regional weather patterns – would make conditions ripe for hurricane formation.
So far, with seven weeks of the official season still to go, there have been nine hurricanes – two more than the Atlantic would typically get.
However, the total number of tropical storms – which includes hurricanes but also weaker storms – has been around average, and less than was expected at the start of the year.
After Beryl weakened, there were only four named storms, and no major hurricanes, until Helene became a tropical storm on 24 September.
That is despite warm waters in the tropical Atlantic, which should favour the growth of these storms.
Across the Main Development Region for hurricanes – an area stretching from the west coast of Africa to the Caribbean