Hurricane Dora was one of few tropical cyclones to track across all three north Pacific basins and the first since Hurricane John in 1994. The fourth named storm, third hurricane, and second major hurricane of the 1999 Pacific hurricane season, Dora developed on August 6 from a tropical wave to the south of Mexico. Forming as a tropical depression, the system gradually strengthened and was upgraded to Tropical Storm Dora later that day. Thereafter Dora began heading in a steadily westward direction, before becoming a hurricane on August 8. Amid warm sea surface temperatures and low wind shear, the storm continued to intensify, eventually peaking as a 140 mph (220 km/h) Category 4 hurricane on August 12.