On May 19, 2010, the National Oceanic and Atmospheric Administration (NOAA) released their forecast for the 2010 Central Pacific hurricane season, which would start on June 1.

The vast majority of the ACE stemmed from Hurricanes Celia and Darby, which collectively accounted for roughly 70 percent of the seasonal total.

[3][16] Inactivity was largely attributed to a moderately strong La Niña event which resulted in below-average sea surface temperatures across the basin.

The displacement of this feature brought conditions that favor tropical development closer to the rugged terrain of Mexico and Central America, a factor known to disrupt low-level circulations.

Accordingly, six of the seven named storms in the Eastern Pacific proper formed east of 106°W, four of which originated over the Gulf of Tehuantepec where the greatest depth of warm waters were restricted to.

However, due to the activity in June, ACE value for the season by the start of August remained slightly above normal, roughly 107 percent the yearly mean.

Attaining peak winds of 45 mph (70 km/h), Agatha soon made landfall late on May 29 near Champerico, Guatemala, just south of the border with Mexico.

In San Juan Bautista Tuxtepec, 82 homes were damaged by flood waters and 40 others were affected in the town of Zimatlán de Alvarez.

Little convective development took place as it traversed the region; however, as it crossed Central America between June 9 and 10, it began to show signs of strengthening.

The newly upgraded storm, now named Blas by the NHC, began to track slowly to the northwest, and later nearly due west, in response to a strengthening ridge over Mexico.

This allowed convection to develop over the center of circulation and that afternoon, the storm attained its peak intensity with winds of 65 mph (105 km/h) and a pressure of 992 mbar (hPa; 29.29 inHg).

Hours later, it degenerated into a non-convective remnant low while situated about 715 mi (1,150 km) west-southwest of the southern tip of Baja California Sur.

Once this shear lightened the next day, Celia rapidly intensified to attain its peak intensity with winds of 160 mph (255 km/h) and an estimated barometric pressure of 921 mbar (hPa; 27.20 inHg).

Over the following 42 hours, sustained winds decreased to tropical storm force and the system began to stall over the open ocean by June 27.

The remnants of Celia continued to drift towards the north before finally dissipating on June 30, about 990 mi (1,590 km) southwest of the southern tip of Baja California Sur.

Initially well-organized, the wave rapidly deteriorated within 24 hours; it continued westward without redevelopment and entered the Eastern Pacific on June 19.

Gradually organizing, the low strengthened into a tropical depression on June 23 while situated roughly 380 mi (610 km) south-southeast of Salina Cruz, Mexico.

At the end of the second phase on June 25, the storm attained its peak intensity as a Category 3 hurricane with winds of 120 mph (195 km/h) and a pressure of 959 mbar (hPa; 28.32 inHg).

[36] Not long after peaking, a large area of westerly winds, produced by Hurricane Alex over the Gulf of Mexico, caused Darby to stall offshore before turning to the east, being drawn into the circulation of the larger storm.

[46] After an unusual, record inactive July, an area of disturbed weather formed off the south coast of Mexico, on August 4 from a tropical wave that left Africa 13 days earlier.

[47] Though the center of Estelle remained offshore, its outer bands brought moderate to heavy rains and increased surf to coastal areas of Guerrero, Michoacán, Colima, and Jalisco on August 7.

Tracking northwestward in response to a mid-level ridge over northwestern Mexico, the depression moved through a region of moderate wind shear, preventing further development.

Located between a strong ridge over Mexico and trough over the north Pacific Ocean, the system tracked northwestward throughout the remainder of its existence.

The crossover of this storm is regarded as an uncommon occurrence,[56] taking place only a handful of times since reliable records in the Atlantic began in 1851.

Tracking westward across the Atlantic, the wave eventually spawned an area of low pressure, which developed into Hurricane Karl on September 14.

Tracking northwestward, the low gradually organized into a tropical depression by September 20, at which time it was situated south of Baja California Sur.

The tropical cyclone worsened Mexico's flooding problem which started when Hurricane Karl made landfall several days earlier.

[73] On December 16, an extratropical cyclone developed in the western Pacific Ocean beneath an upper-level low, just west of the International Date Line.

It quickly intensified into a subtropical storm as it curved to the southeast into an area of warmer than normal water temperatures, which fueled the development of thunderstorms.

The storm soon turned eastward, crossing back into the Central Pacific on December 20 roughly 505 miles (815 km) south of Midway Island.