Does El Niño Typically Skew The End Of Hurricane Season Earlier?

Atlantic hurricane season officially ends Nov. 30, but most seasons have their final named storm well before that date, and it's historically been even earlier in El Niño years.

(MORE: ​October Update For Ongoing El Niño Conditions)

Mid-October begins sharp dropoff in activity for multiple reasons: T​he Atlantic hurricane season runs from June through November to encompass over 97% of Atlantic storms, according to NOAA's Hurricane Research Division.

A​s you can see in the graph below, seasonal activity drops sharply from the mid-September peak into November.

This happens because, while ocean water remains quite warm, wind shear that can rip apart and inhibit tropical storms from forming increases beginning in October.​ Also, tropical waves which move off western Africa into the Atlantic and can often serve as seeds to tropical storms, become less numerous late in the hurricane season.

E​l Niño has historically skewed the formation of the season's final named storm earlier than average: After mid-October, one can usually expect another two storms to form before the end of the season based on the 1991-2020 average, according to the National Hurricane Center.

Early November is when the Atlantic has usually had its final named storm develop since the use of satellites began in 1966.

Of the 19 El Niño years examined in the era of satellites, the last named storm developed earlier than that with an average date of Oct. 25.

E​l Niño seasons ending a bit earlier aligns with what would be expected: The climate phenomenon's warming of the equatorial central and eastern Pacific can influence weather patterns thousands of miles away, including those during hurricane seasons.

Here's where the last storms of the season typically form: The map below shows the tracks of all of the last storms of the season since 1966.

The map shows a mess of tracks in the western and central Atlantic fairly far from land. There are also tracks in the Caribbean Sea and near or over the eastern Gulf and Southeast U.S.

P​art of the reason for this is when these last storms form.

F​or example, in 2002, Lili ended up being the last storm of that hurricane season, due in part to a robust El Niño.

B​ut since that last storm formed in the heart of hurricane season, it was able to intensify in the Gulf of Mexico before it plowed into Louisiana in early October as a hurricane.

T​here are some November U.S. hurricane landfalls on that map, including last year's Hurricane Nicole which made landfall in Florida on Nov. 10. Hurricane Kate is the the latest-in-season U.S. hurricane landfall. Kate made landfall in the Florida Panhandle on Nov. 21, 1985.

Last storms have become major hurricane strikes in Central America and the Caribbean in November: T​here have been a number of destructive last storms of the season recently in Central America, including Hurricane Iota's Category 4 pummeling of Nicaragua in November 2020 and a Thanksgiving landfall in southern Nicaragua from Hurricane Otto in 2016.

F​inally, a pair of recent notable last storms of the season in the Caribbean include Category 4 Hurricane Paloma's raking of the Cayman Islands and eastern Cuba in Nov. 2008, and Hurricane Lenny's Category 4 strike on the northern Leeward Islands the week before Thanksgiving 1999.

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