The 2025 Pacific hurricane season was the first to see twenty named storms since 2018. It was an active Pacific hurricane season with an above average number of tropical cyclones, largely due to warmer than average sea surface temperatures off the western coast of Mexico. In the Eastern Pacific basin (east of 140°W), 18 named storms formed; 11 of those became hurricanes, of which 4 strengthened into major hurricanes. In the Central Pacific basin (between 140°W and the International Date Line), two named storms formed; one of which strengthened into a major hurricane. Additionally, two systems entered into the basin from the east. Collectively, the season had an above-normal accumulated cyclone energy (ACE) value of approximately 127.3 units. The season officially began on May 15, 2025 in the Eastern Pacific, and on June 1 in the Central Pacific; both ended on November 30. These dates, adopted by convention, historically describe the period in each year when most tropical cyclogenesis occurs in these regions of the Pacific.
In contrast to the previous season, which was the latest starting Pacific hurricane season on record in the satellite era, there were several early season storms this year. Tropical Storm Alvin was the first system of the season. It formed off the coast of southern Mexico on May 28, and impacted western Mexico. It was followed by five systems in June, two of which became major hurricanes. Tropical Storm Dalila caused significant flooding in Mexico while passing offshore. Hurricane Erick became the earliest major hurricane to make landfall on either coast of Mexico (Pacific or Atlantic). Erick caused at least US$350 million in damage and 24 fatalities in southwestern Mexico. It was followed by Hurricane Flossie, which passed near the coast of southwestern Mexico, resulting in flooding and property damage. In August, Tropical Storm Ivo brought strong winds and heavy rain to parts of Mexico. In September, Hurricane Lorena, Tropical Storm Mario, and Hurricane Narda brought similar effects to the same region. Then, in October, remnant moisture from Hurricane Priscilla and Tropical Storm Raymond contributed to floods and landslides in several Mexican states and brought heavy rainfall to the Southwestern United States. The last storm of the season, Tropical Storm Sonia, dissipated on October 28, with no further storms forming in November. Despite the level of activity, this was the first Pacific hurricane season since 2022 to not feature a Category 5 hurricane.
Seasonal forecasts
In advance of each Pacific hurricane season, forecasts of hurricane activity are issued by forecasters from the United States National Oceanic and Atmospheric Administration (NOAA)'s Climate Prediction Center, and Mexico's Servicio Meteorológico Nacional (SMN). The forecasts include weekly and monthly changes in significant factors that help determine the amount of tropical storms, hurricanes, and major hurricanes within a particular season.
According to NOAA, the average Pacific hurricane season between 1991 and 2020 contained about 15 named storms, 8 hurricanes and 4 major hurricanes (Category 3 and higher), as well as an accumulated cyclone energy (ACE) index of 80–115 units. Broadly speaking, ACE is the measure of the power of a tropical or subtropical cyclone multiplied by the length of time it existed. ACE is only calculated for full advisories on specific tropical or subtropical cyclones reaching wind speeds of 39 mph (63 km/h) or higher. NOAA typically describes a season as above-average, average, or below-average depending on the cumulative ACE index, but the number of tropical storms, hurricanes or major hurricanes can also be considered.
On May 7, 2025, SMN issued its first outlook for the Pacific hurricane season, forecasting an above average season with 16–20 named storms, 8–11 hurricanes, and 4–6 major hurricanes. On May 22, NOAA released its outlook for the eastern Pacific, which calls for a near-average season with 12 to 18 named storms, 5 to 10 hurricanes, and 2 to 5 major hurricanes, citing a continued neutral phase, the unlikelihood of an El Niño, and the possibility of La Niña in the summer. This increases vertical wind shear in the basin and slightly reduces sea surface temperatures, thus favoring mild to moderate tropical cyclone activity. Furthermore, many global computer models predicted a negative Pacific decadal oscillation (PDO), a phase of a multi-decadal cycle that favored the continuation of much warmer-than-average sea surface temperatures, which had been occurring since 2021, unlike the 1991-2020 period, which generally featured below-normal activity.
Seasonal summary
Officially, the 2025 Pacific hurricane season began on May 15 in the Eastern Pacific, on June 1 in the Central Pacific, and both ended on November 30. Altogether, twenty tropical cyclones have formed, eighteen in the Eastern Pacific and two in the Central Pacific, and all became named storms. Eleven of the storms strengthened into hurricanes, with four of them intensifying into major hurricanes. Activity within the Eastern Pacific began with the formation and development of Tropical Storm Alvin on May 28, two weeks after the official start of the season, but nearly two weeks earlier than the average formation date of the basin's first named storm. Alvin persisted off the coast of Mexico for a few days before degenerating into a remnant low on May 31. The pace of activity quickened in early June. Two storms, Hurricane Barbara and Tropical Storm Cosme, formed on June 8, off the coast of southwestern Mexico. Next came Tropical Storm Dalila, which formed near the coast of southern Mexico on June 13. Hurricane Erick followed early on June 17, off the coast of southern Mexico. Erick was the earliest major hurricane on record to make landfall on either coast of Mexico (Pacific or Atlantic); the previous Pacific coast record was set by Hurricane Kiko on August 26, 1989. Next came Hurricane Flossie on June 29, which became a Category 3 hurricane off the southwestern coast of Mexico Dalila, Erick, and Flossie became the earliest fourth, fifth, and sixth named storms respectively in the Eastern Pacific since official naming of storms began there in 1960.
Tropical activity in the Central Pacific commenced in late July, with the formation of Hurricane Iona on July 27 and Tropical Storm Keli the following day, marking the first time in a decade there were two concurrent named storms that formed in central pacific basin. Both tracked to the south of Island of Hawaiʻi, with Iona crossing the International Date Line. Soon thereafter, Hurricane Gil formed in the open Eastern Pacific on July 31, far south-southwest of the Baja California peninsula. Four tropical cyclones formed during the month of August. The month began with Hurricane Henriette, which formed on August 4 southwest of the Baja California peninsula and eventually moved northeast of Hawaii. It was soon joined by Tropical Storm Ivo on August 6. Systems that developed later in the month were Tropical Storm Juliette on August 24 and Hurricane Kiko on August 31. Each formed well offshore of the southern tip of Baja California. Four systems developed during September: Hurricane Lorena on September 2, Tropical Storm Mario on September 11, Hurricane Narda on September 21, and Hurricane Octave on September 30. In early October, Hurricane Priscilla formed, ultimately paralleling the Southwestern coast of Mexico, causing rain, high surf, and rip currents. Additionally, heavy rainfall was recorded in the Southwestern United States. Tropical Storm Raymond followed, bringing rainfall to Arizona, particularly Pinal County. In late October, Tropical Storm Sonia formed, tracking westward out to sea. This season's ACE index was approximately 127.3 units, as officially calculated by the National Hurricane Center (NHC).
Systems
Tropical Storm Alvin
A large area of disturbed weather formed along the eastern North Pacific monsoon trough, developing a low pressure area on May 25 off the coast of southern Mexico. Between May 26 and 27, the disturbance began organize while moving westward, before turning to the northwest. On May 28 at 18:00 UTC, it developed into Tropical Depression One‑E about 470 mi (760 km) southwest of Acapulco, Mexico.F On May 29 at 12:00 UTC, the depression strengthened into Tropical Storm Alvin. With warm waters and low wind shear, Alvin continued to organize, with satellite imagery showing an increase in convective banding and colder cloud tops. At 18:00 UTC, Alvin peaked with maximum sustained winds of 60 mph (100 km/h) and a minimum central pressure of 999 mbar (29.50 inHg). However, increasing southwesterly wind shear and dry air intrusions caused Alvin to quickly weaken. Alvin then turned north towards the Baja California peninsula due to a ridge over central Mexico. By May 30, all convection in the southern half of the storm collapsed. On May 31, at 06:00 UTC, the system degenerated to a remnant low, and dissipated on June 1, at 06:00 UTC.
The disturbance that spawned Alvin caused heavy rainfall that triggered flash flooding in the Mexican state of Chiapas and neighboring El Salvador. In Chiapas, power outages, downed trees, and damaged vehicles were reported. Eleven homes were damaged and one home was destroyed. Damage was reported across at three communities. A man drowned after he was swept away by floodwaters. In La Libertad, El Salvador, storm surge inundated several businesses. Rough surf injured at least 50 people and twelve people were displaced. Heavy rainfall from Alvin caused flooding, fallen trees, stranded vehicles, power outages, and traffic accidents across Western Mexico. In Manzanillo, Colima, one person was rescued from rough surf. The ports of Cabo San Lucas, San José del Cabo, Huatulco were closed to small boat traffic. Three shelters were opened in Oaxaca. Remnant moisture from Alvin also generated heavy rainfall over Mexico City, damaging roads, downing trees, and trapping vehicles. The Mexico City Metro experienced significant delays due to flooded roadways. Damage was reported across at least four boroughs. Remnant moisture from Alvin triggered severe thunderstorms across the Southwestern United States. Flooding, downed trees, and power outages were reported. In California, at least five stranded were vehicles. Sulphur Springs Valley Electric Company reported that fallen tree branches, strong winds, lightning and heavy rainfall, cut power to 1,400 people in Douglas, Arizona. In New Mexico, one person drowned as a result of freshwater flooding. Damages were estimated to be greater than US$100,000.
Hurricane Barbara
On June 4, a trough of low pressure formed off the coast of southern Mexico. Two days later, showers and thunderstorms associated with the low gradually increased near the Gulf of Tehuantepec. By the morning of June 8, a closed and well-defined low-level circulation had developed within the disturbance, marking the formation of Tropical Storm Barbara. Barbara steadily strengthened into the next day, and by 14:00 UTC on June 9, had become a minimal Category 1 hurricane, with maximum sustained winds of 75 mph (120 km/h) while located about 155 mi (250 km) southwest of Manzanillo, Colima. Later that same day, however, the system weakened, and fell below hurricane strength. Then, on June 10, as Barbara moved through cooler waters and into a less favorable atmospheric environment, its deep convection diminished considerably, and by late that same day, it had degenerated to a remnant low. The remnant low then dissipated two days later.
Periods of heavy rain were reported in Nayarit, Jalisco, Colima, and Michoacán. In Acapulco, minor flooding, fallen trees, power outages, wall collapses, and landslides were reported. Heavy rains damaged a drainpipe, causing wastewater to flood several streets.
Tropical Storm Cosme
On June 6, a broad area of low pressure formed along the western side of an elongated trough south of Mexico. Showers and thunderstorms associated with the low became considerably better organized early on June 8, resulting in the formation of Tropical Depression Three-E. Moving slowly northwestward, the system soon strengthened into Tropical Storm Cosme. Cosme continued to intensify, and by the afternoon of June 9, was nearing hurricane strength, with sustained winds of 70 mph (110 km/h). Additional strengthening was stifled, however, and Cosme began weakening the following morning, due to the effects of moderate northeasterly wind shear and the presence of Barbara to the northeast. Ultimately, all deep convection ceased, and the storm degenerated to a remnant low early on June 11. The remnant low then dissipated early the next day.
Tropical Storm Dalila
On June 10, a broad area of low pressure located several hundred miles south of the Gulf of Tehuantepec began to show signs of organization. Showers and thunderstorms associated with the low increased the following day, though its low-level circulation remained broad and elongated. Due to the increasing likelihood of the system developing into a tropical storm, and its proximity to coastal Mexico, the NHC designated it Potential Tropical Cyclone Four‑E at 21:00 UTC on June 12. The system gradually became better organized, developing into Tropical Depression Four‑E, then soon strengthening into Tropical Storm Dalila at 18:00 UTC on June 13, about 195 mi (315 km) south of Zihuatanejo, Guerrero. The storm continued to gain strength the following day near the coast of southwestern Mexico, its sustained winds reaching 65 mph (100 km/h) that afternoon. However, on the morning of June 15, Dalila began weakening, and it became a remnant low late that day. The remnant low dissipated two days later.