The 1937 Atlantic hurricane season was a below-average period of tropical cyclone activity in the North Atlantic, featuring eleven tropical storms; of these, four became hurricanes. One hurricane reached major hurricane intensity, equivalent to a Category 3 or higher on the modern Saffir–Simpson scale. The United States Weather Bureau defined the season as officially lasting from June 16 to October 16. Tropical cyclones that did not approach populated areas or shipping lanes, especially if they were relatively weak and of short duration, may have remained undetected. Because technologies such as satellite monitoring were not available until the 1960s, historical data on tropical cyclones from this period are often not reliable. As a result of a reanalysis project which analyzed the season in 2012, a tropical storm and a hurricane were added to the Atlantic hurricane database (HURDAT). The official intensities and tracks of all storms were also revised by the reanalysis. The year's first storm formed on July 29 in the Gulf of Mexico, and the final system, a hurricane, dissipated over open ocean on October 21.