Hurricane season ends with 21 named storms

Year was third-most active on books after 2020 set benchmark with 30

The 2021 Atlantic hurricane season ended Tuesday with 21 named storms, four major hurricanes and a new addition to the list of costliest U.S. hurricanes.

Ida, which hit Louisiana on Aug. 29 as a Category 4 hurricane, is now the fifth-costliest storm on record since 1980, with $64.5 billion in damages. It follows Hurricane Katrina from 2005 at $178.8 billion (adjusted based on the 2021 Consumer Price Index), Harvey from 2017 at $138.8 billion, Maria from 2017 at $99.9 billion and Sandy from 2012 at $78.7 billion, according to NOAA’s National Centers for Environmental Information and the National Hurricane Center.

The 2021 hurricane season was the third-most-active year on record in terms of named storms — and it marked the first time that two consecutive hurricane seasons exhausted the list of 21 names. Last year had a record 30 named storms, which prompted the World Meteorological Organization to stop using the Greek alphabet for naming the additional storms. These letters had been designated for especially active seasons when the list of 21 pre-selected names was exhausted.

Of this year’s named storms, seven were hurricanes with winds of 74 mph or greater and four were major hurricanes with winds of 111 mph or greater.

One storm directly affected the Houston area: Hurricane Nicholas made landfall Sept. 14 near the eastern part of Matagorda Peninsula. It did so as a Category 1 storm that brought wind gusts and power outages but it, for the most part, left Houston unscathed.

“Climate factors, which include La Niña, above-normal sea surface temperatures earlier in the season, and above-average West African Monsoon rainfall were the primary contributors for this above-average hurricane season,” Matthew Rosencrans, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, said in a news release.

At the start of hurricane

season, Rosencrans has said both factors could contribute to an active hurricane season. La Niña provides conditions more favorable for storms to develop, whereas El Niño can impede storm development. And disturbances that become tropical storms often come from Africa, so a stronger monsoon (more moisture being pulled into Western Africa) means these disturbances are better positioned to become tropical storms or hurricanes.

In addition, scientists have been tracking a warm phase of sea surface temperature in the North Atlantic Ocean. The sea’s surface temperature has cool and warm phases that may last 20 to 40 years, a natural occurrence that has been happening for at least 1,000 years. This current warm phase, which began in 1995, has favored more, stronger and longer-lasting storms.

Researchers also expect that warmer ocean and air temperatures, rising sea levels and other effects of climate change will fuel stronger hurricanes. The flooding from storm surge could be higher, rainfall could be heavier and winds could be stronger. The percent of storms that reach Category 4 or Category 5, with sustained winds of at least 130 mph, is expected to increase.

The 2022 Atlantic hurricane season starts June 1 — but be prepared for an early storm. The 2021 season marked the seventh consecutive year in which a named storm formed before the official start of hurricane season.