The 1978 Atlantic hurricane season was a slightly above average hurricane season in terms of number of named storms. Eleven tropical cyclones were named in all, and five of these became hurricanes; two of the five became a major hurricane (Category 3 or higher on the Saffir–Simpson scale). This was also the last Atlantic hurricane season to use an all-female naming list. The season officially began on June 1, 1978, and ended on November 30, 1978. These dates, adopted by convention, denote the period in each year when most tropical cyclogenesis occurs in the Atlantic basin. However, the formation of subtropical or tropical cyclones is possible at any time of the year, as shown by the formation of an unnamed subtropical storm on January 18.

Three storms made landfall along the coast of the western Gulf of Mexico during the season. At the end of July and into early August, short-lived Tropical Storm Amelia and its remnants caused extensive flooding in Texas after dropping as much as of rain. There were 33 deaths and US$110 million (equivalent to $ million in ) in damage. Also in August, Tropical Storm Bess made landfall in Veracruz, and later, Tropical Storm Debra did so in Louisiana. Neither caused significant damage, though Debra or its remnants spawned multiple tornadoes that killed two people. Hurricanes Ella and Greta each reached Category 4 strength. Though remaining out at sea, Ella did lash the East Coast of the United States and Atlantic Canada with gusty winds and rip currents in early September. Greta brought strong winds, high tides, and flooding to Central America, particularly Belize and Honduras, resulting in about $25 million in damage and at least five fatalities. The storm crossed intact into the eastern Pacific Ocean and was renamed Olivia. Overall, the storms of this season collectively caused $141 million in damage and 42 fatalities.

Season summary

The Atlantic hurricane season officially began on June 1, 1978. Although 24 tropical cyclones developed, only twelve of them reached tropical storm intensity, which is slightly above the 1966-2009 average of 11.3 named storms per season. Of the twelve tropical storms, five of them strengthened into a hurricane, which is slightly below the 1966-2009 average of 6.2. Two of the five hurricane became major hurricanes, which is Category 3 or greater on the Saffir–Simpson hurricane wind scale. Three tropical storms and two hurricanes made landfall during the season. Collectively, the tropical cyclones of the 1978 season caused at least 42 fatalities and $141 million,

with $6 million in damage and one death in Puerto Rico from the precursor of Hurricane Kendra. The season officially ended on November 30, 1978.

Tropical cyclogenesis began very early, with the development of a subtropical storm on January 18. It dissipated about five days later. However, the next tropical cyclone, an unnumbered depression, did not develop until June 21. In July, there were two systems, including an unnumbered tropical depression and Tropical Storm Amelia. Seven tropical cyclones formed in August, including Tropical Depression Four, tropical storms Bess and Debra and hurricanes Cora and Ella. There were also seven systems in September – tropical depressions Eight, Nine, and Twelve, Tropical Storm Hope, and hurricanes Flossie and Greta. During the month of October, there were five tropical cyclones, with two unnumbered tropical depressions, tropical storms Irma and Juliet, and Hurricane Kendra. There was another unnumbered tropical depression in November, which dissipated on November 5.

The season's activity was reflected with an accumulated cyclone energy (ACE) rating of 63. ACE is a metric used to express the energy used by a tropical cyclone during its lifetime. Therefore, a storm with a longer duration will have high values of ACE. It is only calculated at six-hour increments in which specific tropical and subtropical systems are either at or above sustained wind speeds of 39 mph (63 km/h), which is the threshold for tropical storm intensity.

Systems

Unnamed subtropical storm

In the middle of January, an upper-level trough in the westerlies spawned a surface low-pressure area to the east-northeast of the Lesser Antilles and to the south of a subtropical ridge. Isolated from the detrimental effects of the westerlies, it was initially non-tropical in nature and intensified through a baroclinic energy source, or one that derives energy from the interaction of cold and warm air. Convection increased slightly despite cool sea surface temperatures of around . At 1200 UTC on January 18, it organized into a subtropical depression about east-northeast of Puerto Rico while moving in a general westward track, which it would maintain for much of its duration. The National Hurricane Center (NHC) initiated Dvorak classifications on the cyclone at 0000 UTC on January 19, assessing a Dvorak number of T2.5, suggesting both tropical and subtropical characteristics. On the same day, the pressure gradient between the storm and the ridge produced gale-force winds. By early on January 20, the storm maintained minimal convection near its center, with its primary rainband revolved in a cyclonic formation around its well-defined center. Later that day, the storm strengthened into a subtropical storm and attained peak winds of , supported by both ship and Hurricane Hunters reports.

After the storm maintained peak winds for about 36 hours, the outer rainbands to the south and east of the center began diminishing late on January 21, which began a weakening trend. At around that time, the cyclone was moving west-southwestward, and within 72 hours was forecast by one hurricane forecast model to be located over Hispaniola. By midday on January 22, the winds decreased to below gale force after the convection dissipated near the center. Subsequently, it turned more to the west away from land, and by January 23 the circulation degenerated into a remnant trough about north of the Lesser Antilles. The storm was one of six tropical or subtropical cyclones on record to be active in the month of January, and one of four to have formed in the month.

Tropical Storm Amelia

A tropical wave emerged into the Atlantic Ocean from the west coast of Africa on July 19. The wave did not develop significantly while crossing the Atlantic Ocean and Caribbean Sea. The disturbance then entered an area of the Gulf of Mexico that was conducive to tropical cyclogenesis and became a tropical depression while located about south of Brownsville, Texas on July 30. Despite its proximity to land, the depression strengthened into Tropical Storm Amelia on July 31 and peaked with winds of . Around that time, Amelia made landfall near Port Isabel, Texas. Later on July 31, the storm weakened to a tropical depression and dissipated early the following day.

Amelia affected the Texas coast for two days, causing several shipping incidents and minor damage in Corpus Christi and South Padre Island. While active, there were no deaths linked to the storm. However, the biggest impact from the storm followed its dissipation, when its remnants contributed to record rainfall totals over the state. The state, already suffering from a previous drought, believed that the rain would help alleviate the conditions. However, the dry ground aided the flooding from the storm. The rainfall caused several rivers and creeks to flood, especially around the Texas Hill Country and northern Texas, leading to severe damage. Overall, Amelia caused 33 fatalities with an estimated $110 million in damages.

Tropical Storm Bess

A low-pressure area developed in Georgia along a dissipating cold front on August 1. The system detached from the cold front and drifted southwestward, reaching northeastern Gulf of Mexico on August 3. Satellite imagery, buoys, and reconnaissance aircraft flights indicated that by August 5, the system likely acquired a closed circulation. Thus, the National Hurricane Center estimated that a tropical depression developed in the central Gulf of Mexico at 1200 UTC that day. On August 6, a reconnaissance flight into the depression resulted in an upgrade to Tropical Storm Bess, while located about southeast of Brownsville, Texas. The storm had initially headed west-southwestward at , before moving southwestward at nearly the same speed.

At 1200 UTC on August 7, Bess attained its minimum barometric pressure of . Thereafter, Bess began to turn nearly due southward under the influence of a high-pressure area over southern Texas. Later on August 7, the storm reached its maximum sustained winds of . Early on August 8, Bess made landfall near Nautla, Veracruz, at the same intensity and then rapidly dissipated inland. In Tuxpan, Veracruz and Tampico, Tamaulipas, sustained winds reached only . The storm also produced heavy rainfall, peaking at in La Estrella. However, no flooding occurred and no damage or fatalities were reported. Its remnants emerged into the Pacific Ocean, leading to the formation of Hurricane Iva.

Hurricane Cora

On August 4, a disturbance exited the west coast of Africa and moved quickly westward within the Intertropical Convergence Zone. Two days later, the system broke away from the ICTZ, when it started organizing. It developed into Tropical Depression Three late on August 7. A day later it intensified into Tropical Storm Cora on August 8. The storm quickly intensified and developed a well-defined eye feature. The NHC upgraded Cora to hurricane status, marking only the second time that an Atlantic hurricane was upgraded solely based on satellite photography; the first was Doris in 1975. The NHC estimated that Cora attained peak winds of early on August 9. For much of its duration, Cora moved quickly to the west-southwest toward the Lesser Antilles. Possibly as a result of the fast forward motion, the hurricane weakened soon after reaching its peak intensity, dropping to tropical storm status on August 10. That day, a Hurricane Hunter aircraft encountered the weakening storm. Cora struck the island of Grenada on August 11 while weakening to a tropical depression. Cora degenerated into a tropical wave on August 12 in the eastern Caribbean. The remnant crossed over Central America into the Pacific Ocean, where it regenerated into Hurricane Kristy.

While passing through the Lesser Antilles, Cora produced wind gusts to , along with light rainfall in Barbados and Saint Lucia. In the latter, a person died after stepping on a high tension power line that was downed in Castries. Approximately two to four percent of trees on the island were toppled. Although it remained far to the south, Hurricane Cora affected weather conditions that reached as far north as Presque Isle, Maine, where balloonists Ben Abruzzo, Maxie Anderson, and Larry Newman were preparing to make the first ever transatlantic balloon flight on the Double Eagle II. The winds created by Cora's influence would give the hot air balloon the northerly push required for takeoff.

Tropical Storm Debra