2021 Atlantic hurricane season (Jarrell)

The 2021 Atlantic hurricane season was the first season of a renewed low-activity era (“cold phase”) of tropical cyclone formation in the Atlantic. The season officially began on June 1 and lasted until November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The season was inactive, with 8 total storms forming, of which four were hurricanes. One of those four became major hurricanes, which are Category 3 or higher on the Saffir–Simpson scale.

The first system, Tropical Storm Aaron, developed offshore Florida on June 8 and brushed the Southeastern US Coast before dissipating in the open Atlantic with minimal impact. The season's first hurricane, Bailey, formed in mid-July in the northern Caribbean and struck Louisiana. Bailey caused 11 deaths and produced flooding from Louisiana to Illinois, with damage totaling about $800 million (2021 USD). Tropical Storm Curtis formed in the Atlantic on August 5 and struck Georgia, resulting in 2 fatalities and $35,000 in damages. Hurricane Debra formed in the same area a week later but remained at sea, causing rough seas along the East Coast of the US. Tropical Storm Ethan also resulted in more rough seas when it formed off the coast of North Carolina in early September. Hurricane Gerald became the most devastating storm of the season when it made landfall in eastern Mexico on September 30, and drifted on a westerly course over the country for several more days before dissipating. 59 people were killed as a result of Gerald and $305 million in losses were reported. Tropical Depression Three, as well as Fable and Holly, did not impact land. Collectively, the storms of the 2021 Atlantic hurricane season resulted in 72 fatalities and approximately $1.1 billion in damages.

Seasonal forecasts
In advance of and during each hurricane season, several forecasts of hurricane activity are issued by national meteorological services, scientific agencies, and noted hurricane experts. These include forecasters from the Jarrell Meteorological Center (JMC), Tropical Storm Risk (TSR), the United Kingdom's Met Office (UKMO), and Philip J. Klotzbach, William M. Gray and their associates at Colorado State University (CSU). The forecasts include weekly and monthly changes in significant factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. According to JMC and CSU, the average Atlantic hurricane season between 1991 and 2020 contained roughly 14 tropical storms, seven hurricanes, three major hurricanes, and an accumulated cyclone energy (ACE) index of 72–111 units. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h). NOAA typically categorizes a season as above-average, average, or below-average based on the cumulative ACE index, but the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is sometimes also considered.

Pre-season forecasts
On December 9, 2020, TSR issued an extended range forecast for the 2021 hurricane season, predicting slightly above-average activity with 16 named storms, seven hurricanes, three major hurricanes, and an ACE index of about 127 units. TSR cited the expected development of a weak La Niña during the third quarter of 2021 as the main factor behind their forecast. CSU released their first predictions on April 8, 2021, predicting an above-average season with 17 named storms, eight hurricanes, four major hurricanes, and an ACE index of 150 units, citing the unlikelihood of an El Niño and much warmer than average sea surface temperatures in the subtropical Atlantic. TSR updated their forecast on April 13, with 17 named storms, eight hurricanes, and three major hurricanes, with an ACE index of 134 units. On the same day, University of Arizona (UA) issued its seasonal prediction of above-average hurricane activities, with 18 named storms, eight hurricanes, four major hurricanes, and an ACE index of 137 units. North Carolina State University (NCSU) made its prediction for the season on April 14, calling for an above-average season with 15 to 18 named storms, seven to nine hurricanes, and two to three major hurricanes. On May 13, The Weather Company (TWC) updated their forecast for the season, calling for an active season, with 19 named storms, eight hurricanes, and four major hurricanes. On May 20, NOAA's Climate Prediction Center issued their forecasts for the season, predicting a 60% chance of above-average activity and 30% chance for below-average activity, with 13-20 named storms, 6-10 hurricanes and 3-5 major hurricanes. The following day, UKMO issued their own forecast for the 2021 season, predicting an average one with 14 named storms, seven hurricanes, and three major hurricanes, with a 70% chance that each of these statistics will fall between 9 and 19, 4 and 10, and 1 and 5, respectively.

Mid-season outlooks
In late May and early June, predictions from CSU and TSR were similar to pre-season forecasts due to the a lack of an El Niño and warmer-than-average sea surface temperatures across the Atlantic Ocean. However, by July and August, CSU and TSR all adjusted their forecasts downward because of predictions of cooler-than-average sea surface temperatures and above-average wind shear. JMC also decreased the amount of activity in its final outlook, despite predicting a wetter-than-average western Africa and above-average sea surface temperatures in its report. On August 4, JMC issued its second and final outlook for the season, predicting 9 to 15 named storms, three to six hurricanes, and two to four major hurricanes; these numbers were down significantly from its May outlook. On August 5, TSR issued their final forecast for the season, lowering their numbers to 15 named storms, 7 hurricanes and 3 major hurricanes. Finally, on that same day, Colorado State University issued another update for the season, lowering its numbers slightly. However, the organization continued to state that there was an above-average probability of a United States and Caribbean major hurricane landfall.

Storm names
The following list of names was used for named storms that formed in the North Atlantic in 2021. This particular list had not been used in any previous season, as it was drafted by the Jarrell Meteorological Center (JMC), a independent branch of atmospheric observation and research stationed in Central Texas. It was the first use for all of these names since the post-2016 naming change, except for Debra and Holly; which had been previously used in 1978 and 1976, respectively. Names that were not assigned are marked in. There were no names retired this year; thus, the same list was used again in the 2027 season.

Season effects
This is a table of all the storms that formed in the 2021 Atlantic hurricane season. It includes their duration, names, landfall(s), denoted in parentheses, damages, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a tropical wave, or a low, and all the damage figures are in USD. Potential tropical cyclones are not included in this table.