[1][2] Between 1938, when the United States Weather Bureau began issuing tropical cyclone warnings as a collaborative observation network for cities along the U.S. coastline, and 1963, the season was defined between June 15 and November 15.
As of 2023[update], there have been 92 off-season cyclones recorded in the official Atlantic hurricane database, which dates back to 1851.
Off-season cyclones are most likely to develop in the central to western Atlantic Ocean, and most do not make landfall.
That same storm was estimated to have reached winds of 105 mph (169 km/h), making it the strongest hurricane between December and May; the strongest currently in the official database was a March hurricane in 1908 that reached winds of 100 mph (160 km/h).
Of all cyclones during the off-season, Hurricane Lili in 1984 lasted the longest, for a total of 12 days.
The National Hurricane Center issues names for tropical and subtropical cyclones once their winds reach 39 mph (63 km/h).
Before 1950, storms were numbered based on their appearance in the Atlantic hurricane database; tropical depressions were unnumbered.