The 2015 Pacific hurricane season was the second-most active Pacific hurricane season on record, with 26 named storms, only behind the 1992 season. A record-tying 16 storms became hurricanes, and a record 11 storms further intensified into major hurricanes throughout the season, which would be tied eleven years later. The Central Pacific, the portion of the Northeast Pacific Ocean between the International Date Line and the 140th meridian west, had its most active year on record, with 16 tropical cyclones forming in or entering the basin. Moreover, the season was the fourth-most active season in terms of accumulated cyclone energy, amassing a total of 290.6 units. The season officially started on May 15 in the Eastern Pacific and on June 1 in the Central Pacific; they both ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Northeast Pacific basin. However, the formation of tropical cyclones is possible at any time of the year, as shown when a tropical depression formed on December 31. The above-average activity during the season was attributed in part to the very strong 2014–2016 El Niño event.
The season featured several long-tracking and powerful storms, although land impacts were often minimal. In June, Hurricane Blanca, an early season Category 4 hurricane, killed four people due to rough seas. Hurricane Carlos sustained minor damage while passing a short distance off the coast of Mexico. In July, the remnants of Hurricane Dolores brought record rainfall to Southern California, killing one and causing damage worth over $50 million. On August 29, three Category 4 hurricanes (Kilo, Ignacio, Jimena) were all active simultaneously in the Pacific east of the International Date Line for the first time in recorded history. In September, moisture from Hurricane Linda contributed to storms that killed 21 people in Utah. Later that month, Hurricane Marty inflicted $30 million in damage to the southwestern coast of Mexico. In October, Hurricane Patricia became the most intense hurricane ever recorded in the Western Hemisphere, with a central pressure of 872 mbar (hPa; 25.75 inHg) and 1-minute sustained winds of 215 mph (345 km/h). It also became the strongest landfalling Pacific hurricane on record at the time, until it was surpassed by Hurricane Otis in 2023. Patricia caused 13 fatalities and inflicted $463 million in damage. The season's activity continued into November when Hurricane Sandra became the strongest Pacific hurricane ever recorded in that month. Damage across the basin reached $566 million, while 45 people were killed by the various storms.
Seasonal forecasts
On April 10, 2015, the Servicio Meteorológico Nacional (SMN) issued its first outlook for the Pacific hurricane season, forecasting 19 named storms, 11 hurricanes, and 4 major hurricanes. The organization listed a set of seasons with similar atmospheric and oceanic conditions, including 1982, 1986, 1991, 1994, 2002, and 2014. On May 27, the National Oceanic and Atmospheric Administration's Climate Prediction Center (CPC) released its forecast for the year, highlighting a 70% chance of an above-average season with 15–22 named storms, 7–12 hurricanes, 5–8 major hurricanes, and an accumulated cyclone energy (ACE) index range of 110–190% of the median. While both organizations cited an intensifying El Niño as a cause of increased activity, the CPC also highlighted the difference in global sea surface temperature patterns in 2015 versus the 1995–2014 period. The season ended up exceeding all of these forecasts with 26 named storms, 16 hurricanes, 11 major hurricanes, and an ACE index at more than 200% of the median.
Seasonal summary
The accumulated cyclone energy (ACE) index for the 2015 Pacific hurricane season (Eastern Pacific and Central Pacific combined), as calculated by the National Hurricane Center, was 290.6 units. ACE is a rough measure of the energy generated by a tropical or subtropical cyclone over its lifespan, and is calculated every six hours when the tropical cyclone has sustained wind speeds of at least of 39 mph (63 km/h). Therefore, more intense and longer-lived tropical cyclones will generate more ACE, while tropical depressions are excluded from ACE calculations.
Overall, 31 tropical cyclones formed, of which 26 reached tropical storm intensity and were named. A total of 16 of these storms became hurricanes, and a record-breaking 11 became major hurricanes, which would be tied in 2026. These values make the 2015 season the second-most active on record. The Central Pacific, meanwhile, had its most active year on record, with 16 systems forming or crossing into the basin (8 formed in the basin and 8 others entered into it), surpassing the old record of 11 set in 1992 and 1994. The season officially began on May 15 in the Eastern Pacific, and on June 1 in the Central Pacific; the season ended officially on November 30, though a tropical depression formed well after that on December 31. The well-above-average activity levels were largely attributed to the strong 2014–16 El Niño event, which brought anomalously high sea surface temperatures and low vertical wind shear to western parts of the basin. In fact, for the region between the 116th meridian west and the International Date Line, sea surface temperatures from July to October averaged 28 °C (82 °F), the highest value on record since reliable data records began in 1979. Around Hawaii, sea surface temperatures were 0.9 °C (1.6 °F) higher than at any point during the past 60 years. Wind shear in the region was also at its lowest on record during that period. The existence of a large region of rising air over the basin during much of the season, a feature typical of El Niño events, further facilitated the development and intensification of the season's numerous tropical cyclones.
The season started off with three successive hurricanes, with Andres and Blanca both reaching Category 4 status. On June 3, Blanca became both earliest second hurricane and second major hurricane in the basin since reliable records began in 1971, and became the earliest instance of a landfall on the Baja California Peninsula. Ten days later, Carlos became the second-earliest third hurricane on record. After about a month of inactivity, eight systems formed in July, including five between July 8 and July 12. Ela became the earliest named storm to form in the Central Pacific within the bounds of the official season, and one of the earliest in the calendar year. When Halola and Iune formed soon thereafter, that marked the first month in the satellite era where three tropical cyclones were observed in the Central Pacific simultaneously. Six more systems formed in an active August. Early on August 30, Hurricanes Kilo, Ignacio and Jimena intensified into Category 4 hurricanes. This was the first time in the historical record that three or more major hurricanes existed simultaneously in the Pacific east of the International Date Line, and that two or more major hurricanes existed simultaneously in the Central Pacific.
September saw the formation of five systems, excluding Kevin which was named in September but formed on August 31. Three systems—Linda, Sixteen-E, and Marty—affected Mexico, with the first two also bringing floods to the Southwestern United States. The flood event caused by Linda in Utah was also the state's deadliest. October saw another five systems. With the formation of Oho on October 3, the 2015 season surpassed 1992 and 1994 as the most active year on record in the Central Pacific. During October 18–19, Olaf became the southernmost-forming hurricane and major hurricane in the Eastern Pacific. Olaf later became the first system on record to cross from the Eastern Pacific into the Central Pacific and then back into the Eastern Pacific while still a tropical cyclone. Patricia became the strongest hurricane in the basin on October 23 when its pressure fell to 892 mbar (hPa; 26.34 inHg), breaking the previous record of 902 mbar (hPa; 26.64 inHg) set by 1997's Hurricane Linda. Patricia subsequently became the strongest tropical cyclone on record in the Western Hemisphere in terms of barometric pressure, with a central pressure of 872 mbar (hPa; 25.75 inHg). This value was also the second-lowest globally, behind Typhoon Tip of 1979 which had a central pressure of 870 mbar (hPa; 25.69 inHg). Additionally, its maximum sustained winds of 215 mph (345 km/h) were the strongest ever reliably recorded or estimated anywhere globally. Patricia later became the strongest Pacific hurricane to strike Mexico after making landfall in Jalisco as a strong Category 4 hurricane.
The following month tied for the most active November with the development of two systems, Rick and Sandra. Sandra subsequently strengthened into a major hurricane, bringing the season total to a record 11. Its peak winds of 150 mph (240 km/h) and minimum central pressure of 934 mbar (hPa; 27.58 inHg) surpassed Hurricane Kenneth of 2011 for the strongest November Pacific hurricane in terms of both sustained winds and central pressure. Despite the official end of the season on November 30, anomalously favorable conditions in the Central Pacific gave rise to the final storm of the season, Tropical Depression Nine-C, which formed on December 31 and dissipated late the same day. This marked the latest end to a Pacific hurricane season on record.
Systems
Hurricane Andres
On May 23, the National Hurricane Center (NHC) began monitoring the potential for tropical cyclogenesis well south of Mexico over the following days. A broad low-pressure area formed three days later, steadily organizing to become Tropical Depression One-E at 06:00 UTC on May 28. With an increase in spiral banding and an expanding central dense overcast, the depression was upgraded to Tropical Storm Andres six hours later. Directed west-northwest and eventually northwest by a subtropical ridge over Mexico, the cyclone quickly organized and became a hurricane on May 29. A spurt of intensification saw Andres strengthen into a strong Category 2 hurricane late the next day. Andres's intensification trend leveled off thereafter due to an eyewall replacement cycle and a brief increase in vertical wind shear, but Andres still managed to reach major hurricane status early on May 31, becoming one of only five major hurricanes during the month of May. Although forecasts did not indicate additional strengthening, Andres began a period of rapid deepening the following day as wind shear decreased, intensifying into a Category 4 hurricane at 00:00 UTC on June 1. Andres reached its peak intensity six hours later with maximum sustained winds of 145 mph (235 km/h) and a minimum pressure of 937 mbar (hPa; 27.67 inHg). Thereafter, the system moved west-northwestwards over cooler waters and into a more stable environment, which led to a swift weakening trend. Andres fell below hurricane strength on the morning of June 2, and weakened into a tropical storm a day later. Further weakening ensued as convection around Andres's center dissipated, and the NHC declared Andres a remnant low on June 4.
Moisture extending from the remnants of Andres brought light rain to parts of the Southwest United States, with Phoenix, Arizona having measurable precipitation on June 5 for the first time since records began in 1896. This moisture further extended into Colorado, resulting in scattered severe thunderstorms.
Hurricane Blanca
A tropical wave first monitored by the NHC late on May 27 spawned a weak low-pressure area well south of Acapulco, Mexico, two days later. Plagued by strong upper-level winds from Hurricane Andres, the disturbance slowly organized into the season's second tropical depression at 12:00 UTC on May 31 and further into Tropical Storm Blanca on the following day. Moving little within a weak steering regime, the cyclone began to rapidly deepen by June 2 as conditions aloft became more favorable; following the appearance of a pinhole eye, Blanca became a major hurricane at 12:00 UTC on June 3. Shortly thereafter, Blanca reached its peak intensity as a Category 4 hurricane with winds of 145 mph (235 km/h) and a pressure of 936 mbar (936 hPa; 27.6 inHg). Tremendous upwelling of cooler waters, with some areas falling from 30 to 21 °C (86 to 70 °F), resulted in weakening early on June 4. A concurrent eyewall replacement cycle spurred further weakening and Blanca degraded to Category 1 status by June 5. The next day, a shifting ridge steered Blanca northwest back over warm waters, allowing Blanca to quickly reintensify to a secondary peak of 130 mph (210 km/h). However, as Blanca tracked poleward, waters beneath the cyclone cooled yet again, prompting a quick weakening trend. After weakening to a tropical storm on June 7, Blanca made landfall around 12:00 UTC on June 8, near Puerto Cortés with winds of 45 mph (70 km/h), and became the earliest instance of a landfall in the Baja California Peninsula since records began in 1949. Swiftly weakening over land, Blanca degenerated to a remnant low on June 9 and dissipated shortly after.
On June 3, precautionary alerts were raised across the southern Baja California Peninsula and much of Western Mexico, due to potential impacts from the hurricane. A collective 3,300 troops from the Mexican Army and Navy were deployed to Baja California Sur to ensure the safety of residents. Although Blanca remained far from Jalisco, large swells and rip currents produced by the hurricane claimed four lives. Across Baja California Sur, high winds downed power lines and left 104,106 residents without electricity. However, around 90 percent of the outages were fixed within 12 hours of the storm. The remnants of Blanca later brought much-needed rain to parts of the Southwestern United States. Daily rainfall records were broken in several areas, though accumulations were generally less than 1 in (25 mm). Some flooding took place in Santa Barbara County, California. Flash floods across Nevada inundated homes and roads, and also caused minor damage to landscaping. In New Mexico, strong thunderstorms brought hail of up to 1.75 in (4.4 cm) in diameter, and spawned a brief EF0 tornado near Napi Headquarters. Damage across California amounted to $68,000, while damage across Nevada totaled $46,000. Damage in New Mexico reached $20,000. Additionally, on June 10, some of Blanca's moisture moved north and brought light showers to the San Francisco Bay Area.