The 2021 Pacific hurricane season was a moderately active Pacific hurricane season, with above-average activity in terms of number of named storms, but below-average activity in terms of major hurricanes, as 19 named storms, 8 hurricanes, and 2 major hurricanes formed in all. It also had a near-normal accumulated cyclone energy (ACE). The season officially began on May 15 in the Eastern Pacific Ocean (east of from 140°W), and on June 1 in the Central Pacific (from 140°W to the International Date Line) in the Northern Hemisphere. The season ended in both regions on November 30. These dates historically describe the period each year when most tropical cyclogenesis occurs in these regions of the Pacific and are adopted by convention. However, the formation of tropical cyclones is possible at any time of the year, as illustrated by the formation of Tropical Storm Andres on May 9, which was the earliest forming tropical storm on record in the Eastern Pacific. Conversely, 2021 was the second consecutive season in which no tropical cyclones formed in the Central Pacific.

In June, Tropical Storm Dolores made landfall near the border of the Mexican states of Colima and Michoacán, killing three people and resulting in US$50 million in insured losses. Just a week later, Hurricane Enrique paralleled the west coast of Mexico, causing an additional two fatalities and a similar amount of damage. In August, Hurricane Nora made landfall on the state of Jalisco and paralleled the Pacific coast of Mexico until dissipating, resulting in an estimated $100 million in damage and three more deaths. Less than two weeks later, Hurricane Olaf made landfall on Baja California Sur as a Category 2 hurricane. In October, Hurricane Pamela struck Nayarit at Category 1 intensity, leaving four people missing and severe flooding. Later that month, Hurricane Rick struck near the Michoacán-Guerrero border at peak intensity as a strong Category 2 hurricane. Altogether, five systems made landfall in Mexico in 2021, the greatest number since 2018.

__TOC__

Seasonal forecasts Record Namedstorms Hurricanes Majorhurricanes RefAverage (1991–2020): 15 8 4 Record high activity: 1992: 27 2015: 16 2015: 11 Record low activity: 2010: 8 2010: 3 2003: 0 Date Source Namedstorms Hurricanes Majorhurricanes Ref May 12, 2021 SMN 14–20 7–10 4–5 May 20, 2021 NOAA 12–18 5–10 2–5 Area Namedstorms Hurricanes Majorhurricanes Ref Actual activity: EPAC 19 8 2 Actual activity: CPAC 0 0 0 Actual combined activity: 19 8 2 Forecasts include weekly and monthly changes in important factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. According to the National Oceanic and Atmospheric Administration (NOAA), the average hurricane season in the Eastern and Central Pacific between 1991 and 2020 contained approximately 15 tropical storms, 8 hurricanes, and 4 major hurricanes. The NOAA generally classifies a season as above average, average, or below average based on the cumulative ACE index, but occasionally the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is also considered. Factors they expected to reduce activity were near- or below-average sea surface temperatures across the eastern Pacific and the El Niño–Southern Oscillation remaining in the neutral phase, with the possibility of a La Niña developing.

On May 12, 2021, the Servicio Meteorológico Nacional issued its forecast for the season, predicting a total of 14–20 named storms, 7–10 hurricanes, and 4–5 major hurricanes to develop. On May 20, 2021, the National Oceanic and Atmospheric Administration (NOAA) issued their outlook, calling for a below-normal to near-normal season with 12–18 named storms, 5–10 hurricanes, 2–5 major hurricanes, and an accumulated cyclone energy index of 65% to 120% of the median.

Seasonal summary

The 2021 Pacific hurricane season began on May 15 in the East Pacific and on June 1 in the Central Pacific. Overall activity included 19 named storms, 8 hurricanes, and 2 major hurricanes. The total of named storms was above the 1991–2020 average, while the number of hurricanes was average, and the sum of major hurricanes was below average. The official start date was preceded by the formation of Tropical Storm Andres, the earliest named storm on record in the East Pacific. It was accompanied by Tropical Storm Blanca later in May. The following month included the formations of tropical storms Carlos and Dolores, in addition to Hurricane Enrique. While Carlos remained away from land, Dolores made landfall on the Mexico coastline and Enrique delivered impacts across southwestern sections of the country while it passed just offshore. Above-average seasonal activity continued into July with the development of hurricanes Felicia and Hilda, Tropical Storm Guillermo, and Tropical Depression Nine-E; none of these cyclones impacted land. In August, Hurricane Nora made landfall along the west-central coastline of Mexico. Its formation was preceded by Hurricane Linda and tropical storms Ignacio, Kevin, and Marty, which did not impact land. September marked a stark turn around to the activity of the previous months, as it only featured Olaf, which struck San José del Cabo as a Category 2 hurricane. Two hurricanes – Pamela and Rick – moved ashore the Mexico coastline in October. An additional two storms, Terry and Sandra, developed in November, the fourth consecutive November with at least one named storm. Furthermore, those cyclones existed simultaneously, the first occurrence in the East Pacific during November on record. The Accumulated Cyclone Energy index for the 2021 Pacific hurricane season as calculated by Colorado State University using data from the National Hurricane Center was approximately 94 units, about 30 percent below average.

Systems Tropical Storm Andres

In early May, the passage of a convectively-coupled Kelvin wave (CCKW) enhanced the eastern Pacific monsoon trough, leading to an area of disturbed weather. This disturbance interacted with a Gulf of Tehuantepec gap wind event, which led to the formation of an ill-defined low-pressure area. Despite a marginal environment of wind shear and dry air, the system slowly organized and developed into a tropical depression around 06:00 UTC on May 9. Six hours later, it intensified into Tropical Storm Andres, becoming the earliest tropical storm on record in the East Pacific basin. Andres maintained peak winds of as it curved north-northwest, and the compounded effects of colder waters and drier air atop moderate wind shear instead caused the system to begin weakening. All associated convective activity dissipated by 06:00 UTC on May 11, when Andres was downgraded to a remnant area of low pressure. The low curved west on May 12 and dissipated later that day.

There are no reports of damage or casualties directly associated with Tropical Storm Andres; however, some other rainstorms associated with Andres produced heavy rainfall in Southwestern Mexico. Moisture from the storm caused intense rain and even a hailstorm as far east as the State of Mexico, including in the state's capital, Toluca. Vehicles became stranded in floods, some small trees got knocked over, and about 50 houses were damaged by a flooding river. Four municipalities in the Toluca Valley were flooded; 30 cars were stranded in a flooded parking lot of a church in Metepec, and in Lerma, a shopping center's roof was damaged due to flying debris and hail.

Tropical Storm Blanca

Blanca originated from a tropical wave that crossed Central America on May 27. Shower and thunderstorm activity increased ahead of the wave axis, followed by the formation of a low-pressure area. After further organization, the developed into a tropical depression around 18:00 UTC on May 30. It intensified into Tropical Storm Blanca around 12:00 UTC the next day. Favorable environmental conditions allowed the cyclone to intensify, and it attained peak winds of on June 1 when prominent rainbands wrapped into the center. Thereafter, an upper-level trough off the southwestern United States increased shear over Blanca and injected dry air into the core, resulting in a weakening trend. The storm's low-level circulation became separated from convection, and it degenerated to a remnant low by 00:00 UTC on June 4. The remnants of Blanca, which were previously tracking west-northwest, curved toward the west before dissipating later the next day.

Tropical Storm Carlos

A trough developed within the Intertropical Convergence Zone (ITCZ) on June 1. It moved west across the eastern Pacific for several days but failed to develop into a tropical cyclone on several occasions, either because it lacked a coherent circulation or because it lacked sustained convection. A burst of thunderstorms resulted in the formation of a well-defined center on June 12, and the system steadily organized over ensuing hours, finally resulting in the formation of a tropical depression by 12:00 UTC that day. Six hours later, the depression intensified into Tropical Storm Carlos to the southwest of Baja California Sur. The surrounding environment was initially favorable for development and allowed the system to reach peak winds of as it curves west-southwest. However, increasing dry air around the storm caused Carlos to gradually lose its convection, which ultimately resulted in its degradation to a remnant low by 12:00 UTC on June 16. The remnant system was reabsorbed into the ITCZ the following day.

Tropical Storm Dolores

A broad cyclonic gyre over Central America, spawned from the interaction of the monsoon trough and a tropical wave, led to the formation of an area of low pressure south of Mexico on June 16. The low gradually organized and became a tropical depression around 18:00 UTC on June 17 while located about south-southwest of Acapulco. The depression became Tropical Storm Dolores within six hours. Ridging over Mexico shifted east as Dolores developed, causing the cyclone to curve to the north-northwest. A favorable environment facilitated its development, and the storm reached peak winds of as it made landfall near San Juan de Alima, Michoacán, around 15:00 UTC on June 19. It harbored a well-defined eyewall at the time, and it is possible that Dolores temporarily surpassed tropical storm intensity. Once inland, though, the system quickly weakened over the high terrain of southwestern Mexico, dissipating around 06:00 UTC on June 20.

Dolores produced a wide expanse of or greater rainfall across southwestern Mexico, including a peak accumulation of in Callejones, Colima. At least 20 municipalities in Michoacán were affected by flooding or uprooted trees, blocking many routes through these communities. In Jalisco, the Marabasco River overflowed its banks, briefly isolating 80 homes. Throughout Guerrero, Michoacán, Colima, and Jalisco, more than 50,000 customers lost power. Overall damage to more than 1,000 structures totaled in excess of $50 million. Three people were killed by lightning, two in Oaxaca and one in Jalisco.

Hurricane Enrique