Poll: In what month will the first recorded Atlantic off-season major hurricane form?

[Team Ghost]

Admin: poll created

[Hurricanehink]

I feel like December is more likely than May, but it's a tossup. The latest major hurricane, Otto in 2016, was on November 24, so only a week away from the off-season. Hurricane Alma became a major hurricane on June 8th, 1966. I voted December because of there being more November major hurricanes in recent years (Lenny 99, Michelle 01, Paloma 08, Otto 16, Eta/Iota 20, Rafael 24)

[Category5Kaiju]

Objectively, I think of all the 6 off-season months, we're most likely going to get a December major hurricane, that is if it even happens anytime in the near or far future. It'll also likely happen in the Caribbean Sea during a robust La Nina season. Additionally, if this ever were to even happen in the first place, then I'd bet that it would be a weak Category 3 and nothing stronger than such.

[wwizard]

Surprisingly, of the 32 storms that have formed in May only 4 have become hurricanes. And the last May hurricane was Alma in 1970.

December has the same amount of hurricanes as May but from only 13 tropical storms, and the last December hurricane from a storm that formed in December was Lili in 1984. Epsilon became a hurricane in December but it formed in November and 3 other hurricanes were at hurricane strength in November and crossed into December as hurricanes.

January has the only offseason hurricane in the 21st century, Alex 10 years ago almost to the day, and 2 total of the 5 storms that have formed in January which doesn’t include Alice, which formed in December.

A cat 2 hurricane is in the official database for March (1908). There was another hurricane in May of that year which is the only time there’s been multiple hurricanes before June 1st.

And finally, I was a little shocked to learn that not only has April never had a hurricane, there’s only 3 tropical storms in the official record books that have formed in April, with the first being in 1992. Of course there’s no telling how many were missed pre satellite, but still.

In total, there’s been 55 storms form that have reached tropical storm strength in the offseason months, with 11 of those becoming hurricanes. Those 11 hurricanes are:

Alex (Jan 2016)
Lili (Dec 1984)
Alma (May 1970)
Alice II (Dec 1954)
Twelve (Dec 1951)
Able (May 1951)
One (Jan 1938)
Two (May 1908)
One (Mar 1908)
One (May 1889)
Eighteen (Dec 1887)

All of those except the March hurricane were cat 1.

There’s also a reported cat 2 in May of 1863 nicknamed Amanda, but it’s not recognized by HURDAT.

[CrazyC83]

December is slightly ahead of May IMO.

A December major hurricane would almost certainly be in the deep, deep tropics off the coast of South America, but if a late season CAG combined with a pocket of low shear developed, the opportunity would exist. It is doubtful that such could happen in the Gulf or open Atlantic, since you're relying on an extratropical cyclone transitioning in marginal SST's at best, where category 1 is usually the ceiling.

As for May, it would almost certainly be in the northern Gulf (the only place that is warm enough), but would likely require a storm moving in an unusual track to avoid upwelling while having enough time to intensify. The 1863 storm seems the most likely analog for such. The Caribbean is too stable and the open Atlantic is not warm enough yet or lacking in storm sources.

Just getting a hurricane in the other months is difficult (I know 1908 had that March storm, although category 2 is probably an overestimate).