Tropical Storms Forming in the Off-Season isn't that Strange
An off-season Atlantic hurricane is a recorded tropical or subtropical cyclone that existed in the Atlantic basin outside of the official Atlantic hurricane season.
Since the year 2000 there have been 20 storms that formed outside the season start and end date.
In the official Atlantic hurricane database, which dates back to 1851, the first storm to occur outside of the current season was in 1865 in the Caribbean Sea.
The year with the most off-season storms was 1887, with a total of five existing in the off-season.
The National Oceanic and Atmospheric Administration currently defines the season as occurring between June 1 and November 30 each calendar year, which is when 97% of all Atlantic tropical cyclones occur.