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

With its mighty strength and its dangerous path, Hurricane Milton has powered into a very rare threat that is flirting with experts’ worst fears.

This Oct. 8, 2020 photo made available by the National Oceanic and Atmospheric Administration shows Hurricane Delta in the Gulf of Mexico at 12:41 p.m. EDT. Delta is the sixth storm this year and the second in a week to reach the threshold, Lillo calculated. Hurricanes Hannah, Laura, Sally and Teddy and tropical storm Gamma all gained at least 35 mph (56 kph) in strength in 24 hours. This year is particularly nasty and Delta is a good example, said study co-author Gabriel Vecchi, a Princeton climate scientist. “This season has given a lot of examples of these rapidly intensifying storms that we expect to be more common,” Princeton’s Vecchi said.