The 1940 Atlantic hurricane season was a generally average period of tropical cyclogenesis in 1940. Though the season had no official bounds, most tropical cyclone activity occurred during August and September. Throughout the year, fourteen tropical cyclones formed, of which nine reached tropical storm intensity; six were hurricanes. None of the hurricanes reached major hurricane intensity. Tropical cyclones that did not approach populated areas or shipping lanes, especially if they were relatively weak and of short duration, may have remained undetected. Because technologies such as satellite monitoring were not available until the 1960s, historical data on tropical cyclones from this period are often not reliable. As a result of a reanalysis project which analyzed the season in 2012, an additional hurricane was added to HURDAT. The year's first tropical storm formed on May 19 off the northern coast of Hispaniola. At the time, this was a rare occurrence, as only four other tropical disturbances were known to have formed prior during this period; since then, reanalysis of previous seasons has concluded that there were more than four tropical cyclones in May before 1940. The season's final system was a tropical disturbance situated in the Greater Antilles, which dissipated on November 8.
All three hurricanes in August brought flooding rainfall to areas of the United States. The first became the wettest tropical cyclone recorded in Louisiana history. The second hurricane impacted regions of the Southeastern United States, producing record precipitation and killing at least 52 people. Despite not making landfall, the third hurricane in August interacted with a stationary front over the Mid-Atlantic states, resulting in localized flooding and thus making the tropical cyclone the wettest in New Jersey history. This hurricane would also be the strongest in the hurricane season, with maximum sustained winds of and a minimum barometric pressure of 961 mbar (hPa; 28.39 inHg), making it a high-end Category 2 hurricane on the modern-day Saffir–Simpson hurricane wind scale. Activity decreased in September, though a damaging hurricane swept through areas of the Canadian Maritimes, resulting in large crop and infrastructural losses. Two tropical cyclones of at least tropical storm strength were recorded in October, though neither resulted in fatalities. Collectively, storms in the hurricane season caused 71 fatalities and $29.329 million in damages. The 1940 South Carolina hurricane, which swept through areas of the Southeastern United States in August, was the most damaging and deadly of the tropical cyclones.
The season's activity was reflected with an accumulated cyclone energy (ACE) rating of 68 units, below the 1931–1943 average of 91.2. 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 , which is the threshold for tropical storm intensity. Thus, tropical depressions are not included here. __TOC__
Timeline
Systems Tropical Storm One
On May 18, a weak low-pressure area was detected south of Hispaniola. Moving northward, the low became sufficiently organized to be classified as a tropical storm at 1200 UTC on May 19, southeast of Turks Island. At the time, ship observations indicated that the disturbance had a well-defined cyclonic circulation, with the strongest winds situated in the northern semicircle of the cyclone. Continuing northward, the tropical storm gradually intensified and attained maximum sustained winds of by 0000 UTC on May 22. The Belgian ship M.S. Lubrafol recorded a peripheral barometric pressure of 996 mbar (hPa; 29.42 inHg); this was the lowest pressure measured in connection with the storm. The following day, the tropical storm temporarily curved towards the east-southeast before recurving back towards a northeast direction. At the same time, the storm expanded in size and began to transition into an extratropical cyclone. By 1200 UTC, the cyclone completed its extratropical transition, due to the entrainment of colder air. The remnant system persisted until 0600 UTC on May 27.
Hurricane Two
The 1940 Louisiana Hurricane
On August 3, an extratropical cyclone developed into a tropical depression off the west coast of Florida. Initially a weak disturbance, it moved generally westward, slowly gaining in intensity. Early on August 4, the depression attained tropical storm intensity. Ships in the vicinity of the storm reported a much stronger tropical cyclone than initially suggested. After reaching hurricane strength on August 5 south of the Mississippi River Delta, the storm strengthened further into a modern-day Category 2 hurricane, with maximum sustained winds of and a minimum barometric pressure of at 0600 UTC on August 7. The hurricane moved ashore near Sabine Pass, Texas later that day at peak strength. Once inland, the storm executed a sharp curve to the north and quickly weakened, degenerating into a tropical storm on August 8 before dissipating over Arkansas on August 10.
Reports of a potentially destructive hurricane near the United States Gulf Coast forced thousands of residents in low-lying areas to evacuate prior to the storm moving inland. Offshore, the hurricane generated rough seas and a strong storm surge, peaking at on the western edge of Lake Pontchartrain. The anomalously high tides flooded many of Louisiana's outlying islands, inundating resorts. Strong winds caused moderate infrastructural damage, primarily in Texas, though its impact was mainly to communication networks along the U.S. Gulf Coast which were disrupted by the winds. However, much of the property and crop damage wrought by the hurricane was due to the torrential rainfall it produced in low-lying areas, setting off record floods. Rainfall peaked at in Miller Island off Louisiana, making it the wettest tropical cyclone in state history. Nineteen official weather stations in both Texas and Louisiana observed record 24-hour rainfall totals for the month of August as a result of the slow-moving hurricane. Property, livestock, and crops – especially cotton, corn, and pecan crops – were heavily damaged. Entire ecosystems were also altered by the rainfall. Overall, the storm caused $10.75 million in damages and seven fatalities.
Hurricane Three
The 1940 South Carolina Hurricane
A storm of potentially Cape Verde origin was detected in the Virgin Islands at 1800 UTC on August 5. Initially moving westward, the tropical storm gradually gained in intensity before making a sharp curve towards the north on August 8. The storm continued in a northerly motion before a second curvature brought it in a generally westward direction on August 9. Shortly after, the tropical storm reached hurricane intensity as a modern-day Category 1 hurricane. The hurricane eventually made landfall at peak intensity on Hilton Head Island, South Carolina at 2030 UTC on August 11. At the time, the storm had maximum sustained winds of and a minimum central pressure of , equivalent to a modern-day Category 2 hurricane. Once inland, the tropical cyclone gradually weakened, and recurved northeastward before dissipating over the Appalachian Mountains on August 14.
The hurricane dropped torrential rainfall over the Southeast United States, causing unprecedented devastation in the region. The storm was considered the worst to impact in the region in at least 29 years. Precipitation peaked at in Idlewild, North Carolina. The heavy rainfall caused streams to greatly exceed their respective flood stages, damaging waterfront property. Many of the deaths occurred in North Carolina, where 30 people died. Transportation was disrupted as a result of the debris scattered by the wind and rain. In Caldwell County alone, 90 percent of bridges were swept away. Overall, the storm caused 50 fatalities and $13 million in damages.
Hurricane Four
On August 26, a low-pressure area in the open Atlantic Ocean became sufficiently organized to be classified as a tropical cyclone. Moving slowly in a general west-northwest motion, the disturbance intensified, reaching tropical storm strength on August 28 and subsequently hurricane intensity on August 30. The hurricane passed within of Cape Hatteras before recurving towards the northeast. However, the hurricane continued to intensify, and reached peak intensity as a modern-day Category 2 hurricane with maximum sustained winds of and a minimum barometric pressure of , though these statistical peaks were achieved at different times on September 2. Afterwards, the tropical cyclone began a weakening trend as it proceeded northward, and had degenerated into a tropical storm by the time it made its first landfall on Nova Scotia later that day. The storm transitioned into an extratropical cyclone the next day while making another landfall on New Brunswick. The extratropical remnants persisted into Quebec before merging with a larger extratropical system late on September 3.
Despite not making landfall on the United States, the hurricane caused widespread damage. Extensive precautionary measures were undertaken across the coast, particularly in New England. The heightened precautions were due in part to fears that effects from the storm would be similar to that of a devastating hurricane which struck the region two years prior. Most of the damage associated with the hurricane occurred in New Jersey, where the combination of moisture from the hurricane and a stationary front produced record rainfall, peaking at in the town of Ewan. This would make the storm the wettest in state history. The resultant floods damaged infrastructure, mostly to road networks. Damage in the state amounted to $4 million. Further north in New England, strong winds were reported, though damage remained minimal. Although the storm made two landfalls in Atlantic Canada, damage there too was minimal, and was limited to several boating incidents caused by strong waves. Overall, the hurricane caused $4.05 million in damage, primarily due to flooding in New Jersey, and seven fatalities.
Hurricane Five
A tropical depression was first detected east of the Lesser Antilles on September 7, though at the time weather observations in the area were sparse. The disturbance gradually intensified throughout much of its early formative stages, attaining tropical storm strength on September 10; further strengthening into a hurricane north of Puerto Rico occurred two days later. Shortly thereafter, the hurricane recurved northward, and reached peak intensity the following day as a modern-day Category 2 hurricane with maximum sustained winds of and a minimum barometric pressure of at least . The cyclone steadily weakened thereafter before making landfall on Nova Scotia on September 17 with winds of . Moving into the Gulf of Saint Lawrence later that day, the storm transitioned into an extratropical cyclone. The remnant system curved eastward and passed over Newfoundland before dissipating over the Atlantic on September 19.