Countdown to a Record: Zeta the 27th Storm in 2020 Atlantic Hurricane Season, 1 Shy of Record

 Jonathan Erdman

Published: October 25, 2020

The 2020 Atlantic hurricane season is nearing an all-time record for the number of storms, boosted by the formation of Zeta on Sunday.

Including Zeta, we've seen 27 named storms so far this season.

Only the 2005 season – with 27 named storms and one unnamed storm – remains above 2020 on the list of seasons with the most storms.

2020 may be one storm behind 2005's total, but it's on a record pace. Through Oct. 24, the 2005 hurricane season generated 23 storms – four fewer than 2020, so far.

The 27th storm of the record 2005 season didn't develop until Nov. 29, over a month later in the season than 2020's 27th storm, Zeta.

The 2020 hurricane season exhausted its entire list of names on Sept. 18, having to use the Greek alphabet for subsequent names for only the second time – the first being 2005.

We're already six letters deep into the Greek alphabet. The deepest 2005 went into the Greek alphabet was Zeta (one unnamed storm was added after post-season analysis of the 2005 season, accounting for 2005 only going through Zeta, instead of Eta, in the names list).

(MORE: What Happens If a Hurricane With a Greek Alphabet Name Has to Be Retired?)

Greek names used in 2020 Atlantic hurricane season through Zeta. Names grayed out were not used in the record 2005 Atlantic hurricane season.

Contrasting this storm tally with an average season is even more stunning.

By early October, the average storm count is usually between 10 and 11, according to statistics compiled by Dr. Phil Klotzbach, a tropical scientist at Colorado State University.

After adjusting for past hurricane seasons to account for lower detection of storms, the average storm count for a full season is 13.

So we've had two full average seasons' worth of storms in 2020, so far. And the season isn't over yet.

Number of storms so far in the 2020 Atlantic hurricane season, compared to an average full season (middle bar) and the record 2005 season.

How Many More?

If the rest of the season is just average, we would expect at least one more named storm. That would take the season's tally to 28 storms, equaling the 2005 record and taking us through Eta in the Greek alphabet. However, since there is more than a full month left in hurricane season, we could easily blow by that record.

What if the rest of the season mirrors 2005?

The 2005 season produced another five storms after Oct. 25, not ending until Jan. 6, 2006. That would use up almost half the Greek alphabet, ending with Lambda.

2020 Atlantic hurricane season tracks to-date as of Oct. 25.

There are various other ways to measure the magnitude of a hurricane season.

For example, Zeta is expected to become the 11th hurricane of the season, but nowhere near the record of 15 hurricanes in 2005. There were 14 other seasons in addition to 2005 that produced 10 or more hurricanes most recently in 2017 (10), 2012 (10) and 2010 (12).

By another metric called the ACE index – short for Accumulated Cyclone Energy – which takes into account not just the number, but also the intensity and longevity of storms and hurricanes, 2020 is above average, but well shy of record seasons such as 1893, 1933 and 2005, according to Klotzbach's statistics.

The reason for this: the overwhelming number of shorter-lived storms in 2020. So far, hurricanes Paulette and Teddy were the only two that lasted longer than a week as named storms.

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, IBM.

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, IBM.