The 1963 Atlantic hurricane season was a catastrophic yet average season in terms of tropical cyclone formation, with a total of ten nameable storms. The season officially began on June 15, 1963, and lasted until November 15, 1963. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The first system, an unnamed tropical storm, developed over the Bahamas on June 1.

In late July, Hurricane Arlene, developed between Cape Verde and the Lesser Antilles. The storm later impacted Bermuda, where strong winds resulted in about $300,000 (1963 USD) in damage. During the month of September, Tropical Storm Cindy caused wind damage and flooding in Texas, leaving three deaths and approximately $12.5 million in damage. Hurricane Edith passed through the Lesser Antilles and the eastern Greater Antilles, causing 10 deaths and about $43 million in damage, most of which occurred on Martinique.

The most significant and deadliest system of the season was Hurricane Flora, which peaked as a Category 4 hurricane on the Saffir–Simpson hurricane wind scale. Drifting slowly and executing a cyclonic loop, Flora dropped very heavy rainfall in the Greater Antilles, including over in Cuba. Extreme flooding ensued, leaving behind at least 7,193 fatalities and about $773.4 million in damage. In October, Hurricane Ginny moved erratically offshore the Southeastern United States, though eventually, the extratropical remnants struck Nova Scotia. Ginny caused at least three deaths and $400,000 in damage in the United States alone. The final cyclone, Tropical Storm Helena, caused five deaths and over $500,000 in damage on Guadeloupe. Overall, the storms in this season caused at least 7,214 deaths and about $833.8 million in damage.

Season summary

The 1963 hurricane season officially began on June 15 and ended on November 15. It was an average season with ten tropical storms, slightly above the 1950–2000 average of 9.6 named storms. Seven of these reached hurricane status, which is above the 1950–2000 average of 5.9. Furthermore, three storms reached major hurricane status, which is Category 3 or higher on the Saffir–Simpson hurricane wind scale. Early in the season, activity was suppressed by an abnormally intense trough offshore the East Coast of the United States as well as strong westerly winds. Later, tropical cyclone formation occurred more often after a portion of the trough weakened and easterly flow increased across much of the Atlantic. The tropical cyclones of the 1963 Atlantic hurricane season collectively caused at least 7,214 deaths and $833.8 million in damage.

Tropical cyclogenesis began early, an unnamed tropical storm developing on June 1. However, activity ceased for nearly two months, before Arlene formed on July 31. Another system formed in August, Hurricane Beulah. September was much more active, with Cindy, Debra, an unnumbered tropical depression. Edith, and Flora all developing in that month. Flora was the most intense tropical cyclone of the season, peaking as a Category 4 hurricane with winds of 150 mph (240 km/h) and a minimum barometric pressure of . There were two other system in October, Hurricane Ginny and Tropical Storm Helena; the latter dissipated on October 30.

The season's activity was reflected with an above average accumulated cyclone energy (ACE) rating of 113. ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. It is only calculated for full advisories on tropical systems at or exceeding , which is the threshold for tropical storm strength.

Systems Unnamed tropical storm

Toward the end of May, a tropical disturbance moved northward from Panama toward the western Caribbean Sea. On May 31, a trough moved across eastern Cuba. On June 1, a tropical depression developed over the western Bahamas. Initially, the depression could have been a subtropical cyclone, due to an upper-level low located over the circulation. The depression moved to the northeast and later to the north, strengthening into a tropical storm on June 2. A day later, the storm attained peak winds of 60 mph (95 km/h); on the same day, the storm made landfall just west of Cape Hatteras, North Carolina. By June 4, the storm weakened to a tropical depression as it continued northwestward through Virginia, Maryland, and finally Pennsylvania, where the depression degenerated into a trough.

The disturbance dropped heavy rainfall across Cuba, reaching in Santiago de Cuba. The storm produced gusty winds along the eastern United States coast, from North Carolina through Maryland. Winds reached 40 mph (65 km/h) in Ocean City, Maryland and 39 mph (64 km/h) in Norfolk, Virginia. The latter city recorded of rainfall in a 24-hour period, setting a daily rainfall record for the location. Heavy rainfall reached as far north as Washington, D.C.

Hurricane Arlene

A tropical wave developed into a tropical depression at 18:00 UTC on July 31 while located about halfway between the Lesser Antilles and Cape Verde. It headed west, becoming Tropical Storm Arlene on August 2. Shortly thereafter, Arlene turned to the northeast and bypassed the Lesser Antilles. Around 00:00 UTC on August 5, Arlene weakened back to a tropical depression. Based on ship data and reconnaissance aircraft flights being unable to locate a circulation, Arlene degenerated into a trough about 24 hours later. Observations from ships indicated that the system became a tropical depression again early on August 7. Several hours later, Arlene became a tropical storm again. While curving to the northeast on August 8, the cyclone intensified into a hurricane. Later that day, a Navy reconnaissance plane found hurricane-force winds around the center of the storm, resulting in Arlene being upgraded to a minimal hurricane a second time. Arlene intensified further on August 9 and was a strong Category 2 hurricane by the time it struck Bermuda with winds of 110 mph (175 km/h) at 15:30 UTC. The storm continued to intensify after passing the island, with reconnaissance recorded a minimum pressure of 969 mbar (hPa; ) and maximum winds reached . The hurricane began to weaken hours later, with winds decreasing below by the afternoon of August 10. Shortly after, Arlene transitioned into an extratropical cyclone, while maintaining hurricane-force winds, over the north Atlantic. The extratropical remnants turned east-southeastward and persisted for a few days, until dissipating just north of Madeira on August 14.

Several hurricane warnings and watches were issued for the Leeward Islands. On August 8, after Arlene regenerated, residents in Bermuda were advised to not venture offshore on any vessel and rush all hurricane preparations to completion. In Bermuda, Arlene produced winds up to and a pressure of 974.5 mbar (hPa; ) was recorded during its passage. A maximum gust of was recorded at Kindley Air Force Base. Tree limbs and power lines were downed across the island, a few small boats sank in rough seas and flooding was reported in some areas. Rainfall on Bermuda reached , and the hurricane produced an estimated storm surge. Damages across the island amounted to $300,000.

Hurricane Beulah

A tropical wave emerged into the Atlantic from the west coast of Africa on August 11. The system organized into a tropical depression early on August 20 about northeast of Cayenne, French Guiana. On August 21, the depression intensified into Tropical Storm Beulah while moving to the northwest. Later that day, the first reconnaissance aircraft flight into the storm observed winds of . Based on another reconnaissance flight on August 22 observing a barometric pressure of , Beulah intensified into a hurricane around 18:00 UTC. The storm intensified into a Category 3 hurricane by early on August 24, at which time Beulah attained its peak intensity with maximum sustained winds of 120 mph (195 km/h) and a minimum barometric pressure of . Radar imagery depicted an elliptical eye with a diameter of .

Early on August 25, Beulah weakened significantly due to unfavorable conditions caused by an anticyclone to its south, falling to Category 1 intensity. After leveling off to sustained winds of 80 mph (130 km/h) several hours later, Beulah maintained this intensity for the next few days. Early on August 26, the hurricane turned northeastward under the influence of an upper-level trough offshore the East Coast of the United States. At 00:00 UTC on August 28, the hurricane transitioned into an extratropical cyclone about east-southeast of Cape Race, Newfoundland. The extratropical low eventually turned eastward towards western Europe. The remnants then moved erratically, striking Ireland, the United Kingdom twice, and France before entering the North Sea. On September 8, the remnants finally dissipated north of Jan Mayen.

Unnamed hurricane

As early as September 8, ships north of Puerto Rico reported a weak circulation. Drifting northward, the system developed tropical depression by 12:00 UTC on September 9, while situated about northeast of Turks and Caicos Islands. The cyclone was subtropical in nature, fueled by both latent heat and instability from contrasting cool and warm air masses. While passing Bermuda later on September 10, sustained wind speeds of and decrease in barometric pressure were observed. The system moved east-northeastward and strengthened into a tropical storm late on September 10. The cyclone intensified further and reached hurricane status early on September 12, peaking with maximum sustained winds of 80 mph (130 km/h) and a minimum barometric pressure of . Around that time, the Freiburg observed winds of . Thereafter, the system weakened to a tropical storm about 24 hours later and accelerated to the northeast ahead of a cold front. Around 12:00 UTC on September 14, the storm was absorbed by a large extratropical cyclone while located about north-northwest of Corvo Island in the Azores.

Tropical Storm Cindy

In mid-September, a trough of low pressure was situated in the Gulf of Mexico. The system developed into Tropical Storm Cindy at 12:00 UTC on September 16, while located about south of Cameron, Louisiana. Cindy strengthened while moving north-northwestward. Around that time, the storm attained its peak intensity with maximum winds of 65 mph (100 km/h) and a minimum pressure of . Around 14:00 UTC on September 17, Cindy made landfall near High Island, Texas, at that intensity. After landfall, Cindy weakened to a tropical depression within about 22 hours. Turning southwest, the depression dissipated near Alice, Texas, at 00:00 UTC on September 20.

In southwestern Louisiana, over of rain fell in some areas. Rice crops were flooded, causing about $360,000 in damage. However, the precipitation was described as more beneficial than detrimental. Along the coast, tides inundated roads leading to Cameron and Holly Beach. A man drowned offshore Cameron while evacuating from an oil rig. The storm brought flooding to the southeastern Texas, particularly in and around Port Arthur. Two people drowned in the Port Acres area. Water entered 4,000 homes across Jefferson, Newton, and Orange counties. In Oklahoma, flooding in Guthrie prompted 300 residents to flee their homes; water intruded into 25 businesses and 35 homes. Overall, Cindy caused about $12.5 million in damage, of which $11.7 million stemmed from property damage.

Hurricane Debra