The 2020 Atlantic hurricane season was an extremely active and historic Atlantic hurricane season, which featured the most named storms on record. It featured a total of 31 tropical and subtropical cyclones, with all but one becoming a named storm. Of the 30 named storms, 14 developed into hurricanes, and a record-tying seven further intensified into major hurricanes. It was the second and final season to use the Greek letter storm naming system, the first being 2005, the previous record. Of the 30 named storms, 11 of them made landfall in the contiguous United States, breaking the record of nine set in 1916. During the season, 27 tropical storms established a new record for earliest formation date by storm number. This season also featured a record ten tropical cyclones that underwent rapid intensification, tying it with 1995, as well as tying the record for most Category 4 hurricanes in a singular season in the Atlantic basin. This unprecedented activity was fueled by a La Niña that developed in the summer months of 2020, continuing a stretch of above-average seasonal activity that began in 2016. Despite the record-high activity, this was the first season since 2015 in which no Category 5 hurricanes formed.
The season officially started on June 1 and officially ended on November 30. However, tropical cyclogenesis is possible at any time of the year, as demonstrated by the early formation of Tropical Storms Arthur and Bertha, on May 16 and 27, respectively. This was the sixth consecutive year with a pre-season system and the second of these seasons to have two, with the other being 2016. The first hurricane, Hurricane Hanna, made landfall in Texas on July 25. Hurricane Isaias (2020) formed on July 31, and made landfall in the Bahamas and North Carolina in early August, both times as a Category 1 hurricane; Isaias caused $4.8 billion in damage overall. In late August, Laura made landfall in Louisiana as a Category 4 hurricane, becoming the strongest tropical cyclone on record in terms of wind speed to make landfall in the state, alongside the 1856 Last Island hurricane and Ida. Laura caused at least $19 billion in damage and 77 deaths. September was the most active month on record in the Atlantic, with ten named storms. Slow-moving Hurricane Sally impacted the United States Gulf Coast, causing severe flooding. The Greek alphabet was used for only the second and final time, starting on September 17 with Subtropical Storm Alpha, which made landfall in Portugal on the following day.
Hurricane Zeta struck Louisiana on October 28, becoming the fourth named storm of the season to make landfall in the state, tying the record set in 2002. Zeta also struck the United States later in the calendar year than any major hurricane on record. On the last day of October, Hurricane Eta formed and made landfall in Nicaragua at Category 4 strength on November 3. Eta ultimately led to the deaths of at least 175 people and caused $8.3 billion in damage. Then, on November 10, Tropical Storm Theta became the record-breaking 29th named storm of the season and, three days later, Hurricane Iota formed in the Caribbean. Iota rapidly intensified into a high-end Category 4 hurricane, which also made 2020 the only recorded season with two major hurricanes in November. Iota ultimately made landfall in the same general area of Nicaragua that Eta had just weeks earlier and caused catastrophic damage. Overall, the tropical cyclones of the 2020 Atlantic hurricane season collectively caused at least 432 deaths and over $55.4 billion in damage.
All forecasting agencies predicted above-average activity, some well-above-average, citing factors such as the expectation of low wind shear, abnormally warm sea surface temperatures, and a neutral El Niño–Southern Oscillation or La Niña. Climate change likely played a role in the record-breaking season, with respect to intensity and rainfall. However, each prediction, even those issued during the season, underestimated the actual amount of activity. Early in 2020, officials in the United States expressed concerns the hurricane season could exacerbate the effects of the COVID-19 pandemic for coastal residents due to the potential for a breakdown of safety protocols such as social distancing and stay-at-home orders.
Seasonal forecasts +Predictions of tropical activity in the 2020 seasonSourceDateNamedstormsHurricanesMajorhurricanesRefAverage (1981–2010) 12.1 6.4 2.7 Record high activity30‡157†Record low activity10†0†TSRDecember 19, 20191574CSUApril 2, 20201684TSRApril 7, 20201683UAApril 13, 202019105TWCApril 15, 20201894NCSUApril 17, 202018–228–113–5PSUApril 21, 202015–24n/an/aSMNMay 20, 202015–197–93–4UKMO*May 20, 202013*7*3*NOAAMay 21, 202013–196–103–6TSRMay 28, 20201783CSUJune 4, 20201994UAJune 12, 202017114CSUJuly 7, 20202094TSRJuly 7, 20201884TWCJuly 16, 20202084CSUAugust 5, 202024125TSRAugust 5, 202024104NOAAAugust 6, 202019–257–113–6Actual activity30147* June–November only ‡ New record for activity † Most recent of several such occurrences (See all) Forecasts of hurricane activity are issued before each hurricane season by noted hurricane experts, such as Philip J. Klotzbach and his associates at Colorado State University (CSU), and separately by NOAA forecasters. Klotzbach's team (formerly led by William M. Gray) defined the average (1981 to 2010) hurricane season as featuring 12.1 tropical storms, 6.4 hurricanes, 2.7 major hurricanes (storms reaching at least Category 3 strength in the Saffir–Simpson scale), and an accumulated cyclone energy (ACE) index of 106 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 . NOAA defines a season as above normal, near normal or below normal by a combination of the number of named storms, the number reaching hurricane strength, the number reaching major hurricane strength, and the ACE Index.
The first seasonal forecast was released on December 19, 2019, by Tropical Storm Risk (TSR), a public consortium consisting of experts on insurance, risk management, and seasonal climate forecasting at University College London, anticipating a slightly above-average hurricane season. This forecast was based on the prediction of near-average trade winds and slightly warmer than normal sea surface temperatures as well as a neutral El Niño–Southern Oscillation (ENSO) phase in the equatorial Pacific. In April and May 2020, various agencies issued forecasts for the season, with a hyperactive season predicted by the University of Arizona (UA) and North Carolina State University. The CSU anticipated heightened probabilities for hurricanes striking the Caribbean and the United States. On May 20, the UK Met Office predicted average activity with 13 tropical storms, 7 hurricanes, and 3 major hurricanes. A day later, NOAA released their forecast for an above-normal season, citing the continued ENSO-neutral or even La Niña conditions during the peak of the season.
After the season began, agencies updated their forecasts and generally anticipated an active year. The Atlantic experienced anomalously low wind shear and surface pressures during the month of July, leading to forecasts for a near-record-breaking season. The CSU and TSR predicted a total of 24 named storms, and NOAA predicted between 19 and 25 named storms. This was one of the most active forecasts ever released by NOAA for an Atlantic hurricane season.
Seasonal summary
Background
Overall, the Atlantic tropical cyclones of 2020 collectively resulted in 416 deaths and more than $51.114 billion in damage, making the season one of the costliest on record. The 2020 Atlantic hurricane season officially began on June 1 and ended on November 30. However, tropical cyclogenesis began in the month of May, with tropical storms Arthur and Bertha, marking the sixth consecutive year with an off-season storm. It was the first year with two pre-season storms since 2016, and the first to have two named storms in May since 2012. The season featured 31 tropical depressions, 30 of which became tropical or subtropical storms. The latter total surpassed the previous record of 28 set in 2005. There were 14 hurricanes, which was the second most for a season, behind only 2005. Seven of the hurricanes intensified into major hurricanes, tying 2005 for the most in one season. It was the fifth consecutive Atlantic hurricane season with above average activity, exceeding the previous longest streak of four years between 1998 and 2001. A total of 10 tropical cyclones underwent rapid intensification, tying the record set in 1995.
The season extended the warm phase of the Atlantic multidecadal oscillation ongoing since 1995. The warm AMO tends to produce tropical cyclones that are more intense and have longer durations. The presence of a La Niña contributed to the unprecedented amount of activity. Sea surface temperatures across the Atlantic basin were warmer-than-average. A strong west African monsoon, favorable wind patterns from Africa, weaker vertical wind shear all aided in the formation of tropical cyclones. The ACE index for the 2020 Atlantic hurricane season was 180 units, reflecting the season's well-above-average activity. Climate change likely played a role in the record-breaking season. Scientific American noted that "As the oceans absorb more and more of the excess heat trapped by greenhouse gases, waters will get warmer earlier in the season, which could help set new records in the future." A formal attribution study showed that the extreme rainfall was higher than in a counterfactual without climate change, especially for high-intensity storms. Matthew Rosencrans, the lead forecaster at the National Weather Service, emphasized that climate change has been linked to the intensity of storms and their slow movements, but not to the amount of activity, which might instead be increasing due to improvements in technology.
The season occurred during the COVID-19 pandemic. Early in the year, officials in the United States expressed concerns the hurricane season could potentially exacerbate the effects of the pandemic for U.S. coastal residents. As expressed in an op-ed of the Journal of the American Medical Association, "there exists an inherent incompatibility between strategies for population protection from hurricane hazards: evacuation and sheltering (i.e., transporting and gathering people together in groups)", and "effective approaches to slow the spread of COVID-19: physical distancing and stay-at-home orders (i.e., separating and keeping people apart)." A study published by GeoHealth in December 2020 confirmed a correlation between destination counties (a county in which an evacuee flees to) and an increase in COVID-19 cases.
Record activity