The record-shattering 2020 Atlantic hurricane season just ran out of storm names. A storm that developed in the eastern Atlantic on September 18th was just named Wilfred, the last name on the World Meteorological Organization’s list. With plenty of hurricane season left, any other storms that form this year will be given letters of the Greek alphabet.

The Greek alphabet has only been used once before, during the catastrophic 2005 hurricane season when Hurricane Katrina devastated New Orleans. That year, Wilma was named on October 17th, a full month later than we’re reaching “W” this year.

The practice of naming storms has been in place since the 1950s as a way to help officials share vital information with the public — they figured a name was easier to remember than a number. When a tropical depression reaches sustained wind speeds of 39 miles per hour and becomes a tropical storm, it’s given a name from an alphabetical list of 21 names that rotates every six years.

Some names don’t get reused. If a storm is destructive enough, its name is taken out of commission and is replaced. During that horrendous 2005 season, Katrina, Rita, and Wilma were all devastating enough that their names were retired forever. Fortunately, no names have been retired yet this year — though this season has been notable in other ways.

On Monday, another record was tied: the most tropical cyclones in the Atlantic basin at the same time. The US National Hurricane Center issued advisories that day on five different tropical cyclones over the Atlantic basin. That’s only happened once before in September 1971.

This was also the sixth year in a row that a storm earned its name before the official start of the Atlantic hurricane season on June 1st. Tropical Storm Arthur took shape on May 16th. Hurricanes, which gain strength from heat energy, have also grown stronger over the past 40 years as climate change raises ocean temperatures.

Wilfred is the 21st named storm of the season, which continues until November 30th. An average hurricane season would have only about a dozen storms strong enough to be given a name. NOAA’s Climate Prediction Center forecast a busy season at its onset in June and then raised the number of storms it expected to be named from 19 to 25 in early August. If their revised prediction holds true, that would mean we should get to storm Delta by the end of November.

Correction 11:00am ET: This story has been corrected to state that Wilfred developed in the eastern Atlantic. A previous version stated that it developed in the Gulf of Mexico. We regret the error.

https://www.theverge.com/2020/9/18/21444296/tropical-storm-wilfred-2020-hurricane-season-greek-names