The 2023 Pacific hurricane season was an active and highly destructive Pacific hurricane season which went on to become the costliest on record, primarily due to Hurricane Otis. In the Eastern Pacific basin (east of 140°W), 17 named storms formed; 10 of those became hurricanes, of which 8 strengthened into major hurricanes – double the seasonal average. In the Central Pacific basin (between 140°W and the International Date Line), no tropical cyclones formed for the fourth consecutive season, though four entered into the basin from the east. Collectively, the season had an above-normal accumulated cyclone energy (ACE) value of approximately 168 units. This season saw the return of El Niño and its associated warmer sea surface temperatures in the basin, which fueled the rapid intensification of several powerful storms. It officially began on May 15, 2023 in the Eastern Pacific, and on June 1 in the Central; 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.
Forecasts at the outset of the 2023 season predicted busier-than-normal tropical cyclone activity in the eastern Pacific basin, largely due to El Niño. However, no tropical cyclones developed until June 27, when Hurricane Adrian initially formed, becoming the latest first-named Eastern Pacific tropical storm since Tropical Storm Agatha in 2016. In July, Hurricane Calvin became the season's first major hurricane, later passing just south of the Big Island of Hawaii as a tropical storm, bringing widespread rainfall to the area and neighboring Maui. In August, Category 4 Hurricane Dora passed south of the Hawaiian Islands and contributed to strong gradient winds over Hawaii, which in turn helped fan the flames of multiple devastating wildfires. Later that month, Hurricane Hilary made landfall as a tropical storm in Baja California, later bringing torrential rainfall and gusty winds to the Southwestern United States. In early September, Hurricane Jova, the first Category 5 hurricane in the basin since 2018, caused rainfall, high waves and rip currents in areas previously affected by Hilary.
October saw four tropical cyclones strike the Pacific Coast of Mexico. Tropical Storm Max struck Guerrero on October 9, resulting in intense flooding. Less than two days later, Hurricane Lidia rapidly intensified into a Category 4 hurricane and made landfall at peak intensity on Jalisco. Lidia was followed by Hurricane Norma, which made two landfalls in northwestern Mexico less than two weeks later. Hurricane Otis developed in the time period between Norma's landfalls, rapidly intensified into the second Category 5 hurricane of the season, and devastated Acapulco when it became the first Pacific hurricane to make landfall at Category 5 intensity, therefore surpassing Hurricane Patricia as the strongest landfalling Pacific hurricane on record. Tropical Storm Pilar caused severe flooding in El Salvador and Honduras while passing offshore. In November, the last storm of the season, Ramon, dissipated with no effects to land.
Seasonal forecasts
In advance of each Pacific hurricane season, forecasts of hurricane activity are issued by the United States National Oceanic and Atmospheric Administration (NOAA)'s Climate Prediction Center and Mexico's Servicio Meteorológico Nacional (SMN). These include weekly and monthly changes in significant factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. According to NOAA, the average eastern Pacific hurricane season between 1991 and 2020 contained roughly 15 tropical storms, 8 hurricanes, 4 major hurricanes, with a near-normal accumulated cyclone energy (ACE) index between 80 and 115. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h). NOAA typically categorizes a season as above-average, average, or below-average based on the cumulative ACE index, but the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is sometimes also considered.
On May 4, 2023, SMN issued its forecast for the season, forecasting a total of 16–22 named storms developing, with 7–11 hurricanes, and 3–5 major hurricanes. Factors they expected to increase activity were above-average sea surface temperatures across the eastern Pacific and the El Niño–Southern Oscillation (ENSO) remaining in the neutral phase, with the possibility of a strong El Niño developing. On May 25, 2023, NOAA issued their outlook, calling for an above-normal season with 14–20 named storms overall, 7–11 hurricanes, 4–8 major hurricanes, and an ACE index of 90% to 155% of the median.
Seasonal summary
The accumulated cyclone energy (ACE) index for the 2023 Pacific hurricane season (Eastern Pacific and Central Pacific combined), as calculated by Colorado State University using data from the National Hurricane Center, was 164 units, above the 1991–2020 average of 115 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, a storm with a longer duration, such as Hurricane Dora, which had an ACE of 48.5 units before crossing into the Western Pacific, will have high values of ACE. It is only calculated for full advisories on specific tropical systems reaching or exceeding wind speeds of 39 mph (63 km/h), while tropical depressions are excluded from ACE calculations.
Overall, 20 tropical cyclones formed in the Eastern Pacific, with 17 intensifying into tropical storms. A total of 10 of these storms became hurricanes, and 8 became major hurricanes. The season was very active compared to the more inactive seasons since 2019. No tropical cyclones formed in the Central Pacific, though four did cross into the basin from the east – 1 tropical depression, 2 tropical storms, and 1 hurricane. At least 64 fatalities were recorded and damage totaled at least US$13.07–17.07 billion, mostly due to Hurricane Otis, with most of the rest due to flooding in California from the remnants of Hurricane Hilary. The above-average activity levels were largely attributed to the strong El Niño event, which brought anomalously high sea surface temperatures and low vertical wind shear to western parts of the basin.
The season officially began on May 15 in the Eastern Pacific, and on June 1 in the Central Pacific. The two hurricanes in June were twice the average for the month. However, the season's first storm, Adrian, did not form until June 27, which marked the second-latest date for the first storm of a season. July was below normal, although included the long-lived Hurricane Dora. August was more active and included two major hurricanes, Fernanda and Hilary, the latter of which struck Baja California as a tropical storm. September was quieter than normal with just two named storms, although one, Jova, reached Category 5 on the Saffir-Simpson scale. With five storms, October was the most active month of the season. Although major hurricanes occur every other October in the basin, there were three major hurricanes during the month. The first two, Lidia and Norma, hit Jalisco and Baja California Sur, respectively. The third, Otis, became the first Pacific hurricane to make landfall at Category 5 intensity, causing $12–16 billion (USD) in damage near Acapulco. Also in the month, Tropical Storm Max hit Mexico, and Tropical Storm Pilar produced deadly floods in Central America. The season ended when Tropical Storm Ramon dissipated on November 26.
Systems
Hurricane Adrian
On June 23, a broad area of low pressure formed off the coast of southern Mexico, in an area which the NHC had for several days been monitoring for potential tropical development. The disturbance quickly became better organized on June 27, and intensified to tropical storm at 18:00 UTC, being named Tropical Storm Adrian at 21:00 UTC. Adrian strengthened rapidly, and became the season's first hurricane at 12:00 UTC on June 28, while located about 360 mi (580 km) southwest of Manzanillo, Colima. It then reached Category 2 hurricane status on June 30, with the hurricane maintaining a distinct eye surrounded by a ring of −70 °C (−95 °F) convection on satellite. Adrian reached maximum sustained winds of 105 mph (165 km/h) that day, before entering an environment of stronger wind shear and cool sea surface temperatures, causing it to weaken to a tropical storm the next day. Adrian weakened to a tropical depression early on July 2, and degenerated into a remnant low later that day.
Hurricane Beatriz
On June 25, after dissipating over the central Caribbean, the remnant wave of Atlantic Tropical Storm Bret moved over Central America, merging with a nearby low-pressure area. Slow to organize, the disturbance ultimately coalesced, becoming Tropical Depression Two‑E at 09:00 UTC on June 29. Later, at 21:00 UTC, the depression became Tropical Storm Beatriz while located about 105 mi (170 km) south-southwest of Punta Maldonado, Guerrero. Paralleling the coast, Beatriz was upgraded to a hurricane at 15:00 UTC the next day and soon attained peak winds of 85 mph (140 km/h). An eye began to appear on satellite around this time. However, since Beatriz's circulation was severely disrupted by land interaction, the system weakened to a tropical storm early on July 1, and Beatriz dissipated later that day just offshore from Cabo Corrientes, Jalisco.
In Michoacán, which Beatriz strengthened into a hurricane directly offshore of, strong winds from the cyclone left significant damage across several municipalities. Papaya trees were strewn across the ground from their plantations, while the tile and tin roofs of hundreds of houses were severely damaged or destroyed, particularly in the small town of Maruata. Several communities were left without power for over 48 hours following the storm. Stranded vehicles, fence collapses and fallen trees were reported in the neighboring state of Guerrero, especially around the port city of Acapulco. Despite being well inland of the Pacific coast of Mexico, the state of Hidalgo saw torrential rainfall that flooded nearly 110 homes across three towns; however, no casualties were reported as a result. One person drowned in Mazatlán, Sinaloa, on July 1, while surfing the high waves generated by Beatriz's remnants.
Hurricane Calvin
An area of low pressure formed off the coast of southern Mexico on July 7. The disturbance became better organized over the course of several days, and developed a well-defined center on the afternoon of July 11, becoming Tropical Depression Three-E. By early the next day, the depression had begun developing a central dense overcast, and exhibiting banding features, and then intensified to tropical storm at 06:00 UTC, becoming Tropical Storm Calvin. Calvin moved westward out to sea within a favorable environment with low wind shear and warm sea surface temperatures, and became a Category 1 hurricane at 12:00 UTC on July 13. It then rapidly intensified and became the season's first major hurricane at 18:00 UTC on July 14. It had a well-defined 17-mile-wide (28 km) eye at the time, with a pronounced ring of deep convection surrounding it. A weakening trend began later that day, and by early on July 16, the system had fallen to tropical storm strength. Still moving generally westward, the storm crossed the 140th meridian shortly before 12:00 UTC on July 17, thus entering the central Pacific basin; its sustained winds at the time were near 50 mph (85 km/h). Then, early on July 19, Calvin passed just south of the Island of Hawaiʻi. Weakened by the close encounter with land, the storm began losing its tropical characteristics. Calvin became post-tropical by 18:00 UTC on July 19.
All state parks on the Big Island, as well as most of Hawaiʻi Volcanoes National Park, were shut beginning the afternoon of July 18, while public schools were closed for the whole of July 19. Eight emergency shelters were opened across the county on July 18. Calvin caused no significant damage; only minor flooding occurred in flood-prone areas of the Big Island. Rainfall reached up to 7.24 in (184 mm) at Honolii Stream, while peak gusts of 72 mph (116 km/h) and 70 mph (113 km/h) were recorded on the summits of Haleakalā and Mauna Kea, respectively.
Tropical Depression Four-E
A tropical wave entered the Eastern Pacific on July 16 after moving across Central America. A broad low pressure area associated with the wave formed south of the coast of southwestern Mexico on July 17. The disturbance became better organized by July 20, and at 12:00 UTC, Tropical Depression Four-E formed southwest of the Baja California peninsula. Later that day, however, the depression's structure began deteriorating. It soon lost all of its deep convection, and degenerated into a remnant low by 00:00 UTC on July 22.
Hurricane Dora
A tropical wave which the NHC had been monitoring since July 16 crossed over Central America into the Eastern Pacific on July 29, off the coast of El Salvador, producing a large area of rain and thunderstorms amid a favorable environment. The system became better organized on July 31, and Tropical Depression Five‑E developed that afternoon. Deep convection increased within the depression, and it strengthened into Tropical Storm Dora early the following day. During August 2–3, Dora rapidly intensified to Category 4 strength, far to the southwest of Cabo San Lucas, Baja California Sur. Then, after undergoing an eyewall replacement cycle, and weakening to a Category 3, it re-intensified to Category 4, with sustained winds reaching 140 mph (220 km/h) early on August 4. Later that day and into the next, the system weakened to Category 2, with winds dropping to 105 mph (165 km/h), before rebounding. Dora reached Category 4 for a third time on August 5, with sustained winds of 150 mph (240 km/h). At 15:00 UTC the next day, Dora, experiencing a slight fluctuation in intensity, crossed over into the Central Pacific basin. Later, on the morning of August 9, Dora strengthened once again, generating winds of 145 mph (230 km/h) amid a low-shear, warm sea surface temperatures environment. It continued to display annular characteristics, with a well-defined, symmetrical 9.2-mile-wide (15 km) eye, surrounded by a compact central dense overcast of less than 120 miles (190 km) wide. At 21:00 UTC on August 11, Dora weakened to Category 2 strength about 900 mi (1,450 km) south of Midway Island. It then crossed the International Date Line a few hours later, and was reclassified as Typhoon Dora.