The 1971 Pacific hurricane season began on May 15, 1971 in the eastern Pacific (east of 140°W), and on June 1, 1971 in the Central Pacific (from 140°W to the International Date Line); both ended on November 30, 1971. These dates, adopted by convention, historically describe the period in each year when most tropical cyclogenesis occurs in these regions of the Pacific. It was the first year that continuous Weather satellite coverage existed over the entire Central Pacific. As such, this season is often viewed as the start year for modern reliable tropical cyclone data in the Pacific Ocean.
It was an above average pacific hurricane season with 22 tropical cyclones forming, of which 18 became named storms. During the season, 12 storms became hurricanes, of which 6 became major hurricanes by reaching Category 3 or higher on the Saffir-Simpson Hurricane Scale. At the time, this was a single-season record number of storms. This season also had a record 6 systems make landfall: Agatha, Bridget, Katrina, Lily, Olivia and Priscilla.
Systems
Hurricane Agatha
On May 21, an area of low pressure developed in the very warm waters south of Tehuantepec, Mexico. Later that day, satellite images showed increasing circulation and Tropical Storm Agatha developed shortly after. Agatha continued moving to the west-northwest parallel to the Mexican coastline and strengthened into a hurricane on May 22. A U.S. Air Force weather reconnaissance aircraft flew into Agatha and found an eye and strong bands. The next day, a reconnaissance plane found winds of . On May 24, a ship reported winds of . Agatha made landfall as a Category 2 hurricane on the Saffir-Simpson hurricane scale within of Zihuatanejo, Mexico.
The village of Playa Azul was hard hit by the storm. Up to half of the village's homes were destroyed, and much of the banana, mango, and coconut crops were destroyed.
Hurricane Bridget
A tropical disturbance near El Salvador remained unorganized until June 12. The area of convection started to drift west-northwestward and strengthened into Tropical Depression Two-E. On June 15, the Tropical Depression further intensified into Tropical storm status and was named Bridget, the second tropical storm of the season. Tropical Storm Bridget moved across the Gulf of Tehuantepec which was favorable for Development. On June 16, Bridget continued intensifying and satellite imagery and ship report data confirmed that Bridget had strengthened into a hurricane. Hurricane Bridget continued moving west-northwest along the west coast of Mexico and came within of Acapulco on June 17. Bridget later made landfall as a Tropical Storm about southeast of Manzanillo, Mexico. However, the Tropical Depression Re-entered open waters and dissipated on June 20.
Bridget was the worst hurricane to hit Acapulco in over 25 years; the last strong hurricane to impact Acapulco to a greater extent was the 1943 Mazatlan Hurricane, which made landfall as a Category 3 hurricane and caused $56 million (1971 USD; $ USD) in damage. Hurricane Bridget's storm surge caused flooding in the bay and damaged waterfront and beach facilities. Rough weather and violent seas also sank 20 boats plus a flagship of the Mexican Navy.
Hurricane Carlotta
On July 1 an area of weather developed about east of Clipperton Island. On July 2 the area of thunderstorms strengthened into Tropical Storm Carlotta. An Air Force reconnaissance aircraft flew into Carlotta on July 4 and found a system with a well-defined eye and good outflow, but winds only supported a tropical storm. Another reconnaissance plane found winds that were near hurricane strength on July 4. In post-season analysis, it was discovered that Carlotta was a hurricane for 24 hours on July 3 and 4. Later that day, Carlotta started weakening after moving into a less favorable environment. The storm continued to weaken until dissipating on July 8.
Carlotta stayed over open waters during its entire life and no land was affected.
Hurricane Denise
On July 2 an area of weather got better organized about east of then Tropical Storm Carlotta. On July 4 satellite imagery indicated that the system had strengthened into Tropical Storm Denise and later into Hurricane Denise on July 6. The system continued to move west and on July 7, U.S. Air Force weather reconnaissance plane found a more organized system with sustained winds estimated to be with a minimum central pressure of 963 mbar (hPa; 28.4 inHg). By July 8, the system had sustained one-minute winds of and a minimum central pressure of . Denise reached a peak intensity of , a Category 4 on the Saffir-Simpson Hurricane Scale early on July 9, but then started to weaken.