Timeline of the 2012 Pacific hurricane season

The 2012 Pacific hurricane season was an above-average year for tropical cyclogenesis. The hurricane season officially began on May 15 in the east Pacific—defined as the region east of 140°W—and on June 1 in the central Pacific—defined as the region west of 140°W to the International Date Line—and ended on November 30 in both regions. These dates conventionally delimit the period during each year when most tropical cyclones form in the northeastern Pacific Ocean. This year, the first storm of the season, Tropical Storm Aletta, formed on May 14, and the last, Tropical Storm Rosa, dissipated on November 3. Altogether, seventeen named storms formed; ten became hurricanes, and five further intensified into major hurricanes.

This timeline documents tropical cyclone formations, strengthening, weakening, landfalls, extratropical transitions, and dissipations during the season. It includes information that was not released throughout the season, meaning that data from post-storm reviews by the National Hurricane Center and the Central Pacific Hurricane Center, such as a storm that was not initially warned upon, has been included.

The time stamp for each event is first stated using Coordinated Universal Time (UTC), the 24-hour clock where 00:00 = midnight UTC. The NHC uses both UTC and the time zone where the center of the tropical cyclone is currently located. Prior to 2015, two time zones were utilized in the Eastern Pacific basin: Pacific east of 140°W, and Hawaii−Aleutian from 140°W to the International Date Line. In this timeline, the respective area time is included in parentheses. Additionally, figures for maximum sustained winds and position estimates are rounded to the nearest 5 units (miles, or kilometers), following National Hurricane Center practice. Direct wind observations are rounded to the nearest whole number. Atmospheric pressures are listed to the nearest millibar and nearest hundredth of an inch of mercury.