Their factors supporting an active hurricane season included above average-sea surface temperatures in the subtropical Atlantic Ocean and Caribbean Sea, and a cool neutral ENSO or weak La Niña pattern, corresponding to a low chance of an El Niño.

However, intense wind shear and the suppression of moisture in the atmosphere by the Saharan Air Layer led to an unusual mid-season cessation in tropical cyclogenesis that lasted nearly two months,[28][29] with no named storms in the Atlantic between July 3 and August 31 for the first time since 1941.

After Fiona caused a few billion dollars in damage in Puerto Rico, its remnants struck Nova Scotia as a powerful extratropical cyclone, becoming the costliest weather disaster on record in Atlantic Canada.

Crews of flights conducted by the National Ocean Service took thousands of aerial images of the destruction caused by Ian, which especially assisted with identifying pollutants and areas requiring extensive marine debris cleanup.

Consequently, a gradual increase in deep convection occurred over the Yucatán Peninsula and the northwestern Caribbean Sea, which led to the development of a low-pressure area just north of the Belize-Mexico border on June 2.

Later, after crossing the southern Windward Islands on June 28 and passing near the coast of Venezuela on the following day, the disturbance encountered more favorable conditions but failed to develop a distinct low-level circulation due to its fast forward speed and interaction with land.

[70] In Manteigas, which had been ravaged by intense summer forest fires in nearby areas of the Serra da Estrela mountain range, floods and landslides caused major damage and at least four vehicles were dragged into the Zêzere River.

Convective activity remained sporadic and disorganized for several days as the wave moved generally west-northwestward through an environment of dry air and unfavorable wind shear.

The storm quickly emerged into the Mona Passage and moved west-northwestward until striking the Dominican Republic near Boca de Yuma with winds of 90 mph (150 km/h) around 07:30 UTC on September 19.

The storm accelerated northeastward and then north-northeastward while merging with a cold front several hours later, with Fiona becoming extratropical by 00:00 UTC on September 24 approximately 220 mi (355 km) southeast of Halifax, Nova Scotia.

The remnants of Fiona remained intense and struck Nova Scotia around 07:00 UTC that day and then extreme eastern Quebec on September 25, several hours before reaching the Labrador Sea.

[30] Several of the Leeward Islands recorded tropical storm-force winds and heavy rainfall, with up to 22.22 in (564 mm) of precipitation on Guadeloupe, leading to one death after the overflowing Rivière des Pères swept away a house.

[30] Still recovering from the effects of Hurricane Maria in 2017 and saturated from precipitation produced by Earl,[75] torrential rains fell island-wide on Puerto Rico on September 18–19, exceeding 30 in (760 mm) in some regions, causing destructive flash flooding, landslides, and rockfalls that washed out or blocked numerous roads and bridges.

In Atlantic Canada, strong winds felled thousands of power lines and trees across the region, leaving over 500,000 customers without electricity and causing significant damage to roofs and windows in Nova Scotia.

[31] Early on September 28, Ian struck Dry Tortugas, Florida, with winds of 125 mph (205 km/h) as the storm headed north-northeastward along a broad trough and the western periphery of a subtropical ridge.

[31] While in the early stages of developing, the system brought gusty winds and heavy rain to Trinidad and Tobago,[80][81] the ABC islands, and the northern coast of South America on September 21–22.

[31] Consequently, Ian left extensive impacts to factories, hospitals, roads, tobacco farms, and homes,[82] with more than 100,000 dwellings damaged or destroyed in Pinar del Río Province alone.

Lee County, where Ian made its first landfall in Florida at Category 4 intensity and produced a storm surge which peaked at 7.25 ft (2.21 m) in Fort Myers,[31] reported some degree of impact to 52,514 structures, with 5,369 of those demolished and 14,245 others extensively damaged.

[86] Ian also produced historic flooding across Central Florida due to a wide swath of rainfall totals generally ranging from 10–20 in (250–510 mm),[79] with Osceola, Seminole, and Volusia counties reporting damage or destruction to thousands of buildings and homes.

On account of the shear, Hermine weakened into a tropical depression at 12:00 UTC on September 24, and degenerated into a post-tropical low within 12 hours, while situated about 240 mi (385 km) northwest of Nouadhibou, Mauritania.

By early the following day, the convection became more concentrated and organized around the center, resulting in the formation of Tropical Depression Twelve around 12:00 UTC about 450 mi (720 km) west-southwest of the Cabo Verde Islands.

Moving generally northwestward due to a weakness in a mid-level ridge, the depression encountered strong wind shear, with the center of the cyclone becoming completely exposed from its convection by early the following day.

A strong burst of deep convection developed near the center of the depression as it moved across the Guajira Peninsula in the early morning of October 7, and soon afterward, it strengthened into Tropical Storm Julia over the adjacent southwestern Caribbean.

Julia's relatively quick movement, as well as its passage across areas comparatively less rugged than to the north, caused the cyclone to only gradually weaken, falling to tropical storm intensity late on October 9.

The storm strengthened slightly further that day, peaking with winds of 90 mph (150 km/h) and a minimum pressure of 985 mbar (29.1 inHg) while making landfall in Belize near the mouth of the Sibun River at 21:30 UTC.

Despite Lisa emerging into the Gulf of Mexico early the following day, unfavorable conditions caused the storm to degenerate into a trough of low-pressure by 12:00 UTC on November 5 about 100 mi (160 km) northeast of Veracruz.

[98] Passing over Belize City as it made landfall on November 2, Lisa generated high winds that knocked down trees and electric poles, and damaged several homes; some structures collapsed completely.

However, days of strong on-shore wind flow onto the east coast of Florida produced storm surge that caused severe beach erosion,[55] especially in Brevard, Flagler, St. Johns, and Volusia counties.

Nicole and its remnants produced widespread, but mostly light precipitation across the Southeastern United States before being absorbed by the frontal system, although 7.88 in (200 mm) of rain fell near Foscoe, North Carolina.

[108] Due to the threat the developing system posed to northeastern Mexico and South Texas, the NHC initiated advisories on it as Potential Tropical Cyclone Four at 21:00 UTC that same day.