Otto originated as a subtropical cyclone lingering north of Puerto Rico on October 6, and transitioned into a tropical storm the next day, the fifteenth of the 2010 hurricane season.

[4] Albeit weak, an elongated remnant trough, or area of low pressure, persisted for several days, stalling over the extreme eastern Caribbean Sea as a nearby upper-level cyclonic vortex retrograded to its north.

The low became well defined, interacting with the adjacent upper vortex to produce a wide convective band—a concentrated region in which strong showers and thunderstorms can form—over the northeastern Caribbean.

[6] Over the next day, the system continued to acquire a prominent subtropical structure,[7][8] developing a markedly larger wind radius than typically seen in pure tropical cyclones.

Satellite observations also revealed that although the lower wind circulation was distinct, it had become intertwined with the cyclonic vortex aloft to its southwest, confirming the hybrid nature of the system.

[9] The National Hurricane Center (NHC) thus classified the system as a subtropical depression at 06:00 UTC on October 6, when it was 265 mi (425 km) north-northwest of San Juan, Puerto Rico.

[9] Later, satellite observations showed a rapid improvement in the depression's structure; convective banding wrapped completely around the broad inner wind field, which produced gusts to 65 mph (105 km/h).

[17][18] By 1200 UTC, Otto's winds had reached 75 mph (120 km/h) while a mid-level eyewall began to form, prompting the NHC to upgrade the storm to a Category 1 hurricane south of Bermuda.

[18] Further strengthening ensued as the newly formed hurricane proceeded over the warm waters of the central Atlantic; microwave imagery revealed the eye, though obscured, was vertically well established, marking Otto's peak strength with estimated winds of 85 mph (140 km/h).

[19] Racing northeastward, the hurricane entered an area of progressively cooler waters and adverse upper atmospheric conditions, which eroded its cloud pattern and disrupted the circulation.

[22] Convective activity came to a near halt due to relentless wind shear and a lack of tropical moisture, leading specialists to conclude the storm was entering an extratropical transition.

[25] The post-tropical cyclone decelerated near the Azores over the next week, where it eventually degenerated into a remnant low that recurved sharply southeastward, before completely dissipating west of Morocco on October 18.

Rains and associated floods topped a number of culverts and bridges, washed out the sides of some roadways, and damage to some utility lines, followed by significant disruptions to electricity services.

[45][46] Torrential floods across the islands overturned several cars, and caused extensive damage to utility lines and drainage pipes; dozens of people in Tortola—specifically in Road Town—were temporarily left without power and water.

[50] Widespread flooding from Otto was responsible for substantial increases in damage to the road network across Sint Maartin initially wrought by Earl, amounting to NAƒ1.5 million ($838,000 USD).

[51] On the French side of the island nation, torrents and associated floods in Saint Martin were accountable for similar property infrastructural damage; monetary losses there totaled €800,000 ($1.12 million USD).