Hurricane Sam was a powerful and long-lived Cape Verde hurricane that threatened Bermuda, lasting from late September through early October. It was the fifth longest-lasting intense Atlantic hurricane, as measured by accumulated cyclone energy, since reliable records began in 1966. Sam was the eighteenth named storm, seventh hurricane, and fourth major hurricane of the 2021 Atlantic hurricane season.

The 2021 Atlantic hurricane season was the third-most active Atlantic hurricane season on record in terms of number of tropical cyclones, although many of them were weak and short-lived. With 21 named storms forming, it became the second season in a row and third overall in which the designated 21-name list of storm names was exhausted. Seven of those storms strengthened into a hurricane, four of which reached major hurricane intensity, which is slightly above-average. The season officially began on June 1 and ended on November 30. These dates historically describe the period in each year when most Atlantic tropical cyclones form. However, subtropical or tropical cyclogenesis is possible at any time of the year, as demonstrated by the development of Tropical Storm Ana on May 22, making this the seventh consecutive year in which a storm developed outside of the official season.