The 2021 Atlantic hurricane season was the least active Atlantic hurricane season since 2015, featuring the formation of 14 tropical cyclones, 13 named storms, 5 hurricanes, and only 1 major hurricane (the fewest since 2013). The season officially began on June 1, 2021 and officially ended on November 30, 2021, dates that typically define the start and end of the season. However, the first storm of the season, Tropical Storm Ana, did not form until July 16, the latest first tropical cyclone to form in an Atlantic hurricane season since 2004.
Pre-season forecasts predicted above-average activity due to the expected neutral ENSO conditions during the peak of the season. However, a series of westerly wind bursts resulted in the rapid development of a moderate El Nino by August, which suppressed the Atlantic basin during the 2021 season. In addition, tropical Atlantic sea surface temperatures cooled to their lowest levels since 2018.
Season summary
Storms
Tropical Storm Ana
| Tropical storm (SSHWS) | |
  | |
| Duration | July 16 – July 17 |
|---|---|
| Peak intensity | 65 mph (100 km/h) (1-min) 998 mbar (hPa) |
In mid-July, a stationary front was situated over the western Atlantic. A non-tropical low formed along the western end of this front on July 14. At 06:00 UTC on July 16, it acquired sufficient deep convection to be designated as Subtropical Storm Ana while located north of Bermuda. 18 hours later, deep convection developed closer to the center and Ana transitioned into the first tropical storm of the season. An eye-like feature briefly developed in visible satellite imagery, and Ana reached its peak intensity at 06:00 UTC on July 17. Increasing wind shear and cooling sea surface temperatures caused Ana's deep convection to quickly erode, and Ana became a post-tropical remnant low at 00:00 UTC on July 18, while situated southwest of Newfoundland.
Tropical Storm Bill
| Tropical storm (SSHWS) | |
 | |
| Duration | July 24 – July 25 |
|---|---|
| Peak intensity | 40 mph (65 km/h) (1-min) 1010 mbar (hPa) |
A tropical wave exited the coast of west Africa on July 14. Dry, stable air and strong wind shear in the tropical Atlantic initially limited development. However, the wave entered a more favorable environment near the Bahamas, and developed into a tropical depression at 06:00 UTC on July 24. Six hours later, the depression strengthened into Tropical Storm Bill. Originally, Bill was expected to enter the northeastern Gulf of Mexico and threaten the Northern Gulf Coast as a strong tropical storm. However, moderate wind shear caused the low-level circulation to become exposed, and Bill weakened to a tropical depression at 00:00 UTC on July 25 prior to making landfall near West Palm Beach, Florida. Bill's circulation quickly dissipated as the depression moved inland at 12:00 UTC that same day, and the remnants dissipated shortly thereafter.
Tropical Depression Three
| Tropical depression (SSHWS) | |
 | |
| Duration | August 3 – August 5 |
|---|---|
| Peak intensity | 35 mph (55 km/h) (1-min) 1005 mbar (hPa) |
A tropical wave exited the coast of west Africa on July 22. Due to a strong Azores High, the wave was steered westward with little convective activity for over a week. Convection increased on August 1 as the wave reached the Northwestern Caribbean Sea, but an Air Force Hurricane Hunter aircraft was unable to close off a circulation at this time. The wave crossed the Yucatan Peninsula late on August 2, moving into the Bay of Campeche on August 3. At 18:00 UTC that day, the wave developed into Tropical Depression Three. The depression was initially expected to intensify into a tropical storm, and Tropical Storm Warnings were issued for northern Veracruz. However, the depression remained just short of tropical storm strength, and made landfall near Tampico, Mexico at 01:00 UTC on August 5. The depression's circulation quickly dissipated five hours later due to the mountainous terrain of central Mexico.
Hurricane Claudette
| Category 2 hurricane (SSHWS) | |
 | |
| Duration | August 12 – August 21 |
|---|---|
| Peak intensity | 100 mph (155 km/h) (1-min) 978 mbar (hPa) |
A small tropical disturbance developed within the Atlantic Intertropical Convergence Zone on August 10. A Convectively Coupled Kelvin Wave passed through the tropical Atlantic the next day, leading to an increase in deep convection associated with the disturbance. The disturbance organized into a tropical depression at 12:00 UTC on August 12. Initially, dry air from the Saharan Air Layer limited intensification, but the depression became a tropical storm at 12:00 UTC the next day. At this time, microwave imagery indicated a cyan ring had developed, a common harbinger of rapid intensification. Claudette then quickly organized into the first hurricane of the season at 06:00 UTC on August 14 east of the Lesser Antilles, and reached its peak intensity 12 hours later with maximum sustained winds of 100 mph. Immediately after its peak intensity, strong westerly shear caused Claudette's circulation to become exposed to the west of the convective mass, and Claudette weakened to a tropical storm just 12 hours after its peak intensity. The circulation continued to quickly lose definition, and Claudette opened up into a tropical wave at 06:00 UTC on August 16 over the eastern Caribbean Sea. Claudette's remnants moved northwestward, and reorganized into a tropical depression northeast of the Turks and Caicos Islands at 00:00 UTC on August 18. Claudette slowly intensified as it moved northward and eventually northeastward, and was expected to regain hurricane strength though this did not occur. Claudette transitioned into an extratropical cyclone at 06:00 UTC on August 21, and Claudette's extratropical remnants briefly regained hurricane force winds. Claudette's remnants brought strong wind gusts and heavy rainfall to Newfoundland, though damage was relatively light.
Tropical Storm Danny
| Tropical storm (SSHWS) | |
 | |
| Duration | August 23 – August 27 |
|---|---|
| Peak intensity | 60 mph (95 km/h) (1-min) 1001 mbar (hPa) |
A tropical wave exited the coast of western Africa on August 17. The wave initially moved quickly westward with no development due to dry, stable air. However, deep convection increased on August 22 as the wave approached the Windward Islands. The wave developed tropical storm force winds and a well-defined circulation early on August 23 based on ASCAT data, and Tropical Storm Danny formed at 18:00 UTC that day. Danny was initially expected to intensify into a Category 1 hurricane over the eastern Caribbean Sea and pose a long-range threat to the Yucatan Peninsula. However, only modest intensification occurred due to strong southwesterly shear, and Danny attained its peak intensity at 18:00 UTC on August 24 with maximum sustained winds of 60 mph. Subsidence, dry air, and strong shear caused Danny to struggle over the next two days, though it remained intact as a tropical storm over the eastern Caribbean Sea. Danny weakened to a tropical depression at 18:00 UTC on August 26, and opened up into a tropical wave at 06:00 UTC on August 27.
Hurricane Elsa
| Category 1 hurricane (SSHWS) | |
 | |
| Duration | August 26 – September 4 |
|---|---|
| Peak intensity | 85 mph (140 km/h) (1-min) 982 mbar (hPa) |
A vigorous tropical wave exited the coast of western Africa on August 24, and quickly developed into a tropical depression at 12:00 UTC on August 26 while located southwest of Cabo Verde. Moving west-northwestward, the depression strengthened into Tropical Storm Elsa 12 hours later. Due to light wind shear and marginally warm waters, Elsa gradually strengthened into a hurricane by 12:00 UTC on August 28. However, a temporary increase in shear due to an upper-level low to Elsa's west resulted in Elsa weakening to a tropical storm 12 hours later. Elsa restrengthened into a hurricane at 12:00 UTC on August 29. At 18:00 UTC on August 29, Elsa reached its peak intensity with maximum sustained winds of 85 mph. Despite very light shear at this time, only marginal sea surface temperatures of 26°C (78.8°F) prevented further intensification. As sea surface temperatures cooled further, Elsa weakened to a tropical storm at 00:00 UTC on August 31. Due to weak steering currents, Elsa completed a cyclonic loop on September 1. Elsa then accelerated east-northeastward the next day, though environmental conditions were not conducive for reintensification. Elsa became a post-tropical remnant low at 06:00 UTC on September 4 as deep convection dissipated, while located west-southwest of the Azores.
Tropical Storm Fred
| Tropical storm (SSHWS) | |
 | |
| Duration | September 1 – September 4 |
|---|---|
| Peak intensity | 45 mph (75 km/h) (1-min) 1002 mbar (hPa) |
In late August, an upper-level trough developed near the Bahamas. The upper-level trough moved westward into the eastern Gulf of Mexico, and began to acquire tropical characteristics. At 12:00 UTC on September 1, the system developed into a tropical depression over the northern Gulf of Mexico. The depression was steered west-northwestward by a ridge to its north, and strengthened into Tropical Storm Fred at 06:00 UTC on September 2. Moderate wind shear prevented rapid organization, and Fred made landfall over eastern Texas with maximum sustained winds of 45 mph at 00:00 UTC on September 3. Fred moved inland over Texas, and dissipated at 06:00 UTC on September 4.
Tropical Storm Grace
| Tropical storm (SSHWS) | |
 | |
| Duration | September 11 – September 15 |
|---|---|
| Peak intensity | 50 mph (85 km/h) (1-min) 999 mbar (hPa) |
After an unusual week of inactivity in early September, a non-tropical low over the central Atlantic developed into a tropical depression at 18:00 UTC on September 11. Just six hours later, it strengthened into Tropical Storm Grace. Due to moderate wind shear, Grace was unable to strengthen significantly, reaching its peak intensity at 00:00 UTC on September 13 with maximum sustained winds of 45 mph. Later that day, Grace turned to the north, and the low-level circulation became exposed. On September 14, Grace turned eastward, and weakened to a tropical depression. Grace degenerated into a remnant low at 12:00 UTC on September 15, after it became devoid of deep convection. Grace's remnants dissipated the next day well west of the Azores.
Hurricane Henri
| Category 4 hurricane (SSHWS) | |
 | |
| Duration | September 14 – September 24 |
|---|---|
| Peak intensity | 130 mph (215 km/h) (1-min) 951 mbar (hPa) |
A tropical wave moved off the coast of western Africa on September 11. Deep convection began to increase on September 13, with the development of some banding features late that day. The wave developed into a tropical depression at 12:00 UTC on September 14, strengthening into Tropical Storm Henri 18 hours later. However, Henri's fast movement caused the circulation to open up into a trough at 00:00 UTC on September 17. As Henri's forward speed slowed down, it regenerated into a tropical storm at 18:00 UTC on September 18. Henri then turned northwestward and strengthened, becoming a hurricane 24 hours later. At 18:00 UTC on September 20, Henri became the first major hurricane of the season, and reached its peak intensity six hours later with maximum sustained winds of 130 mph. Henri then slowly weakened as it recurved well east of Bermuda, weakening to a tropical storm late on September 23. As Henri accelerated, it transitioned to an extratropical cyclone at 06:00 UTC on September 24. Henri's extratropical remnants brought flooding and tropical storm force winds to Ireland and the United Kingdom.