Significant Off-Season Atlantic Hurricanes

Hurricane Epsilon on December 5, 2005  (Source: NOAA)

Hurricane season runs from June through November in the Atlantic Ocean Basin, which includes the Gulf of Mexico and Caribbean Sea.  September is the busiest month of the hurricane season because conditions are most favorable for development.  However, there have also been a handful of noteworthy off-season hurricanes in the Atlantic Ocean.

Alex (2016) – Alex was a minimal Category 1 hurricane with peak winds of 85 mph and a minimum central air pressure of 981 millibars (mb) on January 14 while south of the Azores.  Although a weak hurricane, the mere fact it developed in the central Atlantic in January is a rare occurrence.  Alex was the Atlantic’s first January hurricane since Alice in 1955.  Ironically, the second named storm of the 2016, Tropical Storm Bonnie, also developed before the official start of hurricane season in late May.

Epsilon (2005) – The 2005 hurricane season saw a record number of tropical storms (28) and hurricanes (15) in the Atlantic Ocean.  Epsilon was significant not for its intensity, but for being the final hurricane of the record season.  Since the 2005 season had so many named storms, the entire list of assigned names was used up and names from the Greek alphabet had to be added.  Epsilon reached hurricane intensity on December 2 and had sustained winds of 85 mph and a minimum pressure of 981 mb at peak intensity.  Epsilon became the Atlantic’s longest lasting December hurricane on record, remaining at hurricane intensity for five days.

Lili (1984) – Lili was the Atlantic’s first December hurricane since an unnamed 1951 storm.  At peak intensity over the central Atlantic Ocean, Lili had sustained winds of 80 mph and a minimum central pressure of 980 mb.  This version of Lili was a relatively benign storm when compared to the 2002 version.  Some may recall that 2002 version of Hurricane Lili was a damaging and deadly hurricane that ultimately made landfall in Louisiana on October 3.  The name “Lili” was subsequently retired by the World Meteorological Organization before the start of the 2003 season.

Alma (1970) – Alma was the last Atlantic hurricane to develop during the month of May.  Alma reached its peak intensity on May 20 with sustained winds of 80 mph and a minimum central air pressure of 993 mb, while located near the Cayman Islands and Jamaica.  Eventually, the remnants of Alma spread appreciable rainfall from Florida to Virginia. 

Off-season hurricanes are noteworthy for the fact they occur so infrequently.  That said, an off-season tropical storm or hurricane has occurred in 11 of the last 20 years in the Atlantic Ocean – including Tropical Storm Arlene this past April.