Hurricanes in May?

 

Tropical Storm Arlene, April 2017 (Source: NOAA)

Hurricane season runs from June 1 through November 30 with the busiest months being August and September. June is typically a quiet month in the tropics, but tropical storms and hurricanes do occur sometimes. Every so often tropical storms also develop before the season officially gets underway.

Although unusual, having a named storm develop before June 1 has occurred more often in recent years. At least one named storm has developed early in the Atlantic a total of nine times since 2012. A system becomes a “tropical storm” and is given a name when the sustained winds around its center reach 39 mph. If sustained winds reach 74 mph, then the tropical storm becomes a hurricane.

On occasion, a named storm has characteristics of both a tropical system and a non-tropical area of low pressure. Under such circumstances, the system is classified as a “subtropical storm.”  That’s what happened with Tropical Storm Alberto in May 2018. It began as a subtropical storm in the Gulf of Mexico. However, it eventually became a fully tropical storm before it made landfall in the Florida panhandle on May 29.

Alberto was also significant for making 2018 one of seven consecutive years at least one named storm formed prior to the official start of the hurricane season. That broke the previous record for most consecutive years that a tropical storm developed prior to June 1 (1951 – 1954).

In January 2016, Hurricane Alex developed south of the Azores and was the first Atlantic hurricane during the month of January since 1955. Some may wonder if having a named storm prior to the official start of hurricane season is a reliable indicator of whether or not a given season will be an active one. Quite simply, it isn’t. If conditions are favorable for a tropical storm to develop prior to June 1, it isn’t a guarantee that conditions will remain favorable for an active hurricane season as a whole.

If a tropical storm or hurricane develops before this June 1, it would be the first season since 2023 that’s occurred in the Atlantic Ocean. The first named storm of 2026 will be given the name “Arthur.”