Cabo Verde Season is Upon Us

August marks the start of the busiest stretch of the Atlantic hurricane season

With Monday marking the first day of August, the Atlantic turns the page to primetime hurricane season. It’s during the months of August, September, and October that the Atlantic comes alive – often unnervingly fast. Seemingly overnight, forecast models light up, each disturbance requires more babysitting, and meteorologists hit the refresh button on model websites more often than they’d care to admit. Three months can feel like three years during busy seasons, and for those impacted, hurricane fatigue quickly sets in. Usually about the time we start wondering where all the storms are is when the tropics kick into high gear. Mother Nature can be cruel like that.

In August, we also turn to the eastern Atlantic and look off the coast of Africa for the start of Cabo Verde Season. The storms that form near the small island country of Cabo Verde – which sits roughly 400 miles west of Africa – and grow into hurricanes before reaching the Caribbean gain a special designation from hurricane forecasters. Cabo Verde Hurricanes don’t form often, but the ones that do come to life in August and September, and their long tracks through the Atlantic allow them to strengthen into some of our most powerful and destructive hurricanes. The Great 1928 Lake Okeechobee (or San Felipe Segundo Hurricane), which killed an estimated 3,000 people, was a Cabo Verde Hurricane. So was the Great 1938 New England Hurricane (also known as the Long Island Express), Hurricane Donna in 1960, Hurricane Hugo in 1989, and Hurricane Irma in 2017. The list isn’t long, but the hurricanes are notorious.

The origin of Cabo Verde Hurricanes – called Cape Verde Hurricanes prior to 2013, when the island country officially changed its English name – dates back to the early 20th century when hurricanes developed in the far eastern Atlantic outside the bounds of early weather charts. Forecasters began calling these storms “Cape Verde Hurricanes.” One of the great early books on Atlantic hurricanes – aptly titled Atlantic Hurricanes, written in 1960 by pioneering hurricane scientists Gordon Dunn and Banner Miller (Dunn, the first official National Hurricane Center Director, and Miller, an early NHC scientist for whom the most prestigious award in tropical meteorology is eponymously named, both Miami residents) – describes these unique storms:

“During August and early September, some storms do reach hurricane intensity within 10° to 15° longitude of the Cape Verdes and if they remain on a fairly straight westerly course and move steadily along at around 15 mph, they will approach the United States coast line as very large and severe hurricanes. The Miami and West Palm Beach hurricanes of 1926 and 1928 were good examples of the Cape Verde type. However, the great majority of August and early September hurricanes develop west of longitudes 45° and 50° and should not be included in the Cape Verde classification.”

While no official definition exists for Cabo Verde Hurricanes, they’re generally considered tropical storms that form within 500 to 600 miles of the Cabo Verde Islands and become hurricanes before reaching the Caribbean. Fewer than 70 hurricanes of the 948 Atlantic hurricanes on record (dating back to 1851) meet these criteria – or fewer than one in ten hurricanes. Since the advent of continuous weather satellites, we’re able to detect these storms more easily, but even in the modern record, these elite hurricanes are observed only about once every one to two years.

Early hurricane forecasters had it right. Cabo Verde Hurricanes form primarily in August and September. Nearly all Cabo Verde Hurricanes we know about have come together in these two months.

Of the Cabo Verde Hurricanes that have struck the U.S., they also tend to show a preference toward Puerto Rico, the U.S. Virgin Islands, and the mainland Atlantic coastline, though occasionally they do make it as far west as the Gulf of Mexico.

Hurricanes arrive on their own timelines, but when they do it’s often in rapid succession. If history’s any indication – and it usually is – in the next three to four weeks, we’ll see the pace pick up as Cabo Verde Season falls upon the Atlantic.