At a Glance

In recent years, storms have often formed before the hurricane season's official June start.But it's been over 50 years since the last May hurricane.A few of these have scraped close to the East Coast.One even made a Gulf Coast landfall during the Civil War.

The Atlantic hurricane season doesn't officially start until June, but there have been a few May hurricanes in the past, one of which made a U.S. landfall during the Civil War.

We've discussed the recent propensity for the hurricane season to .

At least one named storm has formed prior to June 1 in 11 of the last 19 years through 2021, including the past seven years in a row.

Officially, the Atlantic hurricane season runs from June through November. That time frame was selected to encompass 97% of all Atlantic tropical storms and hurricanes, according to NOAA's Hurricane Research Division.

But in the graph below, you can see there has been some activity in May.

Named storms and hurricanes per day from 1944 through 2020 in the Atlantic Basin. The arrow denotes activity in May.

(NOAA/NHC)

That includes a small number of hurricanes.

According to NOAA's historical database, only four May hurricanes since the late 19th century have been documented in the Atlantic Basin.

That's because ocean water typically isn't warm enough in May to support hurricanes. Wind shear – the change in wind speed and/or direction with height – also tends to be strong before June and can rip apart tropical systems before they can organize.

The Last One Was in 1970

It's been over 50 years since the last May hurricane, and it only happened briefly.

In just one day's time, the 1970 season's first tropical depression rapidly intensified to a Category 1 hurricane west of Jamaica on May 20. Almost immediately after that, it succumbed to strong wind shear and weakened to a depression near the Cayman Islands.

After dumping heavy rain in the western two-thirds of Cuba, Alma was pulled northward into the southeastern U.S., wringing out from Florida to the Carolinas.

ESSA satellite image of Hurricane Alma over the western Caribbean Sea on May 20, 1970.

(NOAA)

East Coast Brushes

Three other May hurricanes formed off the East Coast.

Tracks of May Atlantic hurricanes since 1889. Portions of tracks during which they were hurricanes are shown in red. (Black section of the May 1889 track indicates when it was a post-tropical remnnant.)

In 1951, Hurricane Able developed from what was once a cold upper-level low between Bermuda and the northwest Bahamas. It reached hurricane strength as its center sunk southward near Grand Bahama Island on May 18, then turned north and remained a Category 1 hurricane just east of North Carolina's Outer Banks before turning east and out to sea.

This happened nine years before the launch of the first weather satellite - TIROS 1 - and over a decade before satellite imagery of the entire Atlantic Basin became standard.

The only way forecasters knew about this bizarre preseason hurricane at the time was after a ship east of Daytona Beach, Florida, reported 50 to 60 mph winds and waves up to 30 feet, according to the "A Preseason Hurricane of Subtropical Origin."

A reconnaissance mission later that day found there was, indeed, a hurricane centered just 80 miles off Florida's coast.

Prior to the era of reconnaissance aircraft missions, ship logs and land reports provided the best evidence of past hurricanes.

In 1908, a late-May Category 1 hurricane with a brief landfall. Another May hurricane was found to have split between Bermuda and the Outer Banks in .

A Once-Forgotten May Hurricane

A by Michael Chenoweth and C.J. Mock unearthed a once-forgotten Civil War-era U.S. hurricane in late May 1863.

Named Amanda in honor of a Union ship driven ashore, this is the first known May U.S. hurricane landfall on record.

It came ashore in the Florida Panhandle on May 28 and killed at least 110 people.

Amanda almost reached major hurricane - Category 3 - status before striking Florida. That would've been almost a month sooner than the current earliest-in-season U.S. major hurricane landfall, on June 27, 1957, in southwest Louisiana.

Track history of Hurricane Amanda from May 24-29, 1863.

(NOAA/NHC)

The National Hurricane Center has not adjusted the start of hurricane season earlier to account for preseason storms. However, beginning last year, they began issuing routine Atlantic tropical weather outlooks on May 15, rather than June 1.

(MORE: 2022 Atlantic Hurricane Season Outlook)

Don't expect another May hurricane any time soon, but it's a reminder that now is a good time to .

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, .