2015 Pacific hurricane season

An El Niño season far above normal

For most of 2015 the northeastern Pacific sat under a strong El Niño. Ocean temperatures ran well above normal across the basin, vertical wind shear was unusually low and the air held more moisture than usual. Near Hawaii, sea surface temperatures were the warmest for any month in more than 60 years, beating the previous record by about 0.9°C. Those conditions favored storms far to the west of where Eastern Pacific activity usually concentrates, and the Central Pacific Hurricane Center logged a record 15 tropical cyclones in its basin.

The site's archive records 26 tropical storms, 17 hurricanes, 11 major hurricanes and one Category 5, with accumulated cyclone energy (ACE) of 329.6. Before the season, NOAA's Climate Prediction Center had called for 15 to 22 named storms, 7 to 12 hurricanes and 5 to 8 major hurricanes; the season exceeded the top of every range. NOAA's long-term average is about 15 named storms, 8 hurricanes and 4 major hurricanes.

Season summaries built on the NHC and CPHC best track list 26 named storms, 16 hurricanes and 11 major hurricanes, with an ACE of 290.2 calculated by Colorado State University. They count each storm only while it was inside the Eastern and Central Pacific basins. The site's counts follow US-agency one-minute winds over each storm's whole tropical track during the calendar year, including time spent west of the International Date Line. Halola explains the extra hurricane: it was a tropical storm while east of the Date Line and became a typhoon after crossing it. Time west of the Date Line for Halola and Kilo also adds to the site's ACE.

How the season unfolded

The first tropical-stage observation came on 28 May, and the season opened with three hurricanes in a row. Andres reached Category 4 over open water and was only the fifth major hurricane to form in May since reliable records began in 1971. Blanca followed within days, becoming the earliest second hurricane and earliest second major hurricane of an eastern North Pacific season. Carlos, a tiny hurricane, hugged the southern coast of Mexico in mid-June.

After Carlos faded on 17 June, three weeks passed without a new tropical cyclone. Then five systems formed between 8 and 12 July: Ela, Halola and Iune in or near the Central Pacific, Dolores off southern Mexico and Enrique farther west. Halola crossed the Date Line just before 13 July. Felicia, Tropical Depression Eight-E and Guillermo followed later in the month, with Guillermo crossing into the Central Pacific and dissipating just north of the Hawaiian Islands.

August brought the season's most crowded stretch. Hilda became a major hurricane before entering the Central Pacific and passed south of Hawaii. Loke and Kilo formed in the Central Pacific, while Ignacio and Jimena developed farther east. By 30 August Kilo, Ignacio and Jimena were all Category 4 hurricanes at the same time, the first time three major hurricanes had been observed together east of the Date Line. Kilo went on to cross the Date Line on 1 September, the third tropical cyclone to do so that year, and its track in the archive spans about 27 days, the longest of the season.

Activity kept coming through the autumn. September produced Kevin, Linda, Malia, Tropical Depression Sixteen-E, Niala and Marty. October added Oho, which formed south of Hawaii and tracked northeast, Tropical Depression Eight-C, Nora, Olaf and Patricia. November still produced Rick and Sandra. The last tropical-stage observation in the archive is Sandra's on 28 November, although a final depression, Nine-C, formed near the equator on 31 December.

Patricia and the season's other major hurricanes

Hurricane Patricia was the season's strongest storm by a wide margin. The archive records a peak of 185 kt and 872 hPa at 12:00 UTC on 23 October, south of Mexico. In the 24 hours ending at 06:00 UTC that day, its winds rose from 75 kt to 180 kt while it crossed waters of 30.5 to 31°C, the warmest observed in that region in mid-October. The National Hurricane Center ranks Patricia as the strongest hurricane on record in the eastern North Pacific and North Atlantic basins, and its 872 hPa pressure as the lowest on record in the Western Hemisphere and second lowest worldwide.

Ten other storms reached major hurricane strength, spread from late May to late November. Jimena peaked at 135 kt and 932 hPa on 29 August, while Olaf and Sandra both reached 130 kt. Andres, Blanca, Hilda and Ignacio each peaked at 125 kt, Kilo at 120 kt, Dolores at 115 kt and Linda at 110 kt.

Several of these set their own records. Olaf is the lowest-latitude hurricane on record in the eastern Pacific and the only Category 4 on record south of 10°N. Sandra, which peaked at 934 hPa on 26 November, is the latest-forming major hurricane of the satellite era in the eastern North Pacific.

Landfalls and impacts

Patricia made landfall around 23:00 UTC on 23 October near Playa Cuixmala in Jalisco, on a sparsely populated stretch of coast. It had weakened rapidly on approach, and NHC estimates the landfall intensity at 130 kt with a central pressure of 932 hPa, the lowest analyzed for a Pacific hurricane striking Mexico. NHC counted two direct deaths, campers killed by a falling tree, and four indirect deaths in a road accident. More than 10,000 homes were damaged or destroyed, about 100,000 acres of farmland were severely affected, and media reports put preliminary damage at 5.4 billion Mexican pesos, about US$325 million at 2015 values.

Earlier landfalls were weaker. Blanca came ashore on Baja California Sur on 8 June with winds near 40 kt, the earliest tropical storm landfall on the peninsula in the reliable record, and NHC received no reports of damage or casualties. Carlos struck near Tenacatita on 17 June as a tropical storm of about 45 kt after rapid weakening; high surf and rain caused at least 5 million pesos (US$326,000 in 2015) of damage to coastal structures near Lázaro Cárdenas.

Much of the season's damage in Mexico came from rain. Tropical Depression Sixteen-E moved ashore over Baja California Sur and northwestern Mexico on 21 September, and flooding around El Fuerte, Sinaloa, caused preliminary damage estimated at 300 million pesos (US$17.7 million in 2015). Marty caused no reported deaths, but its rains flooded 300 homes west of Acapulco, and its remnants caused an estimated 500 million pesos (US$30 million in 2015) of damage in Guaymas, Sonora.

Moisture from several storms reached the southwestern United States. Dolores passed close enough to Socorro Island to bring hurricane conditions there, and its moisture partly fed rare July downpours across southern and central California, though NHC did not attribute that damage to the storm. NHC recorded no casualties or damage from Linda itself, but moisture partly from Linda contributed to flash floods in Utah on 14 September that killed 20 people, the state's deadliest flood event.

Hawaii escaped a direct hit despite the crowded Central Pacific. NHC's report on Ignacio notes flash flooding on Oahu on 3 September that inundated some businesses in Honolulu, with no damage total available. Kilo brought tropical storm conditions to Johnston Island as its center passed about 35 miles to the north on 28 August.

Names and other records

Eight named storms formed between 140°W and the Date Line and took names from the Central Pacific lists: Ela, Halola, Iune, Kilo, Loke, Malia, Niala and Oho. Kilo was named before Loke because it was operationally declared a depression on 20 August; post-storm analysis moved its formation to 22 August, a day after Loke. Olaf became the only tropical cyclone on record to move from the eastern Pacific into the central Pacific and back again.

In April 2016 the World Meteorological Organization retired the name Patricia because of the storm's extreme intensity. Pamela replaced it on the list used in 2021.