Hurricane Tomas was a moderately powerful late-season tropical cyclone which became the latest Atlantic hurricane on record in the calendar year to strike the Windward Islands. The nineteenth named storm and twelfth hurricane of the 2010 Atlantic hurricane season, Tomas developed from a tropical wave east of the Windward Islands on October 29. Quickly intensifying into a hurricane, it moved through the Windward Islands and passed over Saint Lucia. After reaching Category 2 status on the Saffir–Simpson scale, Tomas quickly weakened to a tropical storm in the central Caribbean Sea, due to strong wind shear and dry air. Tomas later reintensified into a hurricane near the Windward passage.

Along the hurricane's path, 44 fatalities occurred, 8 of whom were in Saint Lucia. In the wake of the storm in Haiti, flooding exacerbated a cholera outbreak, indirectly causing more fatalities. However, direct impacts from the hurricane in Haiti were less than anticipated. Overall damage from the storm was $463.4 million.

A tropical wave exited the western coast of Africa on October 24. It moved hastily westward across the tropical Atlantic at a comparatively low latitude, becoming embedded within the Intertropical Convergence Zone. During this time the wave's structure retained a vigorous appearance; the western portion contained scattered convection, with strong thunderstorms, as well as a broad area of rotating winds. On October 27, when the system was about 1,200 miles (1,900 km) east-southeast of the Windward Islands, the National Hurricane Center (NHC) noted favorable atmospheric conditions for tropical cyclogenesis, namely light wind shear. The wave and its expansive convection amplified over the next two days, featuring hints of spiraling rainbands. A Hurricane Hunters aircraft investigating the disturbance on October 29 observed a developing circulation with tropical storm-force winds at sea level. In light of those features, the NHC estimated that the system became a tropical depression by 06:00 UTC that day, about 460 mi (740 km) southeast of Barbados, and further upgraded it to Tropical Storm Tomas six hours later.

On its inception, Tomas turned toward the northwest and decelerated within a region of low wind shear and high tropical moisture—two of the prime prerequisites of rapid intensification. A misalignment between the cyclone's low- and upper-level circulations impeded this strengthening potential, however, and at that time the NHC did not expect Tomas to attain hurricane status until 36 to 48 hours later. Steered along high pressure to its north, the storm retraced slightly west-northwestward on its approach to the Windward Islands. Despite the prior forecasts of moderated strengthening, Tomas' winds sharply increased to 60 mph (97 km/h) by late October 29; moreover, the outflow aloft became well established in all quadrants as the convection consolidated into a prominent rain band. The center of the intensifying storm crossed southern Barbados the next morning, around 09:00 UTC. Radar images from Martinique soon revealed the formation of an eye-like feature; Tomas attained hurricane status a couple of hours later, about 35 miles (56 km) east of Saint Vincent and the Grenadines, after Hurricane Hunters recorded surface winds of 75 mph (121 km/h). By that time, the eye measured 35–46 mi (56–74 km) in diameter.

Tomas continued to strengthen through October 30 as it moved generally west- to west-northwestward. Around 20:00 UTC, the eye traversed the northern shores of Saint Vincent, while the northernmost ring of the severest winds skirted Saint Lucia. Subsequent reports from Hurricane Hunters and post-storm reanalysis indicated that Tomas had reached a peak intensity with wind speeds of 100 mph (160 km/h) and a minimum pressure of 982 mbar (hPa; 29.00 inHg) during its trek across the islands, making it a Category 2 on the Saffir–Simpson hurricane scale. Although the NHC noted the potential for Tomas to become a major hurricane, the agency conversely observed that the hurricane had begun to suffer from southwesterly wind shear, which computer models forecast to increase in the long term. On October 31, a combination of this shear and pockets of dry air dispersed the convection surrounding the eye, initiating a weakening trend. Tomas diminished to a tropical storm early on November 1, when the strongest thunderstorms became dislocated from the low-level wind vortex by more than 115 mi (185 km). Tomas meandered slightly south of west for a while, passing north of the ABC Islands overnight. Although the upper wind regime relaxed into the next day, with an area of deep convection briefly reblossoming near Tomas' center, the shear appeared to have already taken its toll on the storm. With an increasingly diffuse and elongated structure, Tomas further weakened to a tropical depression at 00:00 UTC, November 3, about 325 miles (523 km) southeast of Kingston, Jamaica.

Following its deterioration, Tomas diverged toward the northwest over the central Caribbean. The circulation lost further definition, adjoining a wide stretch of low pressures spanning the western Caribbean. A Hurricane Hunters mission to determine whether Tomas retained its status as a tropical cyclone found that the mean low-level circulation had reformed to the northeast of the previous center. Tomas reattained tropical storm strength late on November 3, and although the low- and mid-level centers were initially nonaligned, slow restrengthening ensued into the next day. Tomas turned northward ahead of an unseasonably strong deep-layered trough, circumnavigating the western periphery of the subtropical ridge. Over a six-hour period, the cyclone's core thunderstorm activity became much more concentrated, with a corresponding quick drop in central pressure. While turning northeastward into the Windward Passage, Tomas regained hurricane status around 0600 UTC on November 5, just 36 miles (58 km) west-southwest of the western tip of Haiti.

Over the course of November 5, the hurricane accelerated northeastward in response to the approaching trough, passing right between eastern Cuba and western Haiti. Due to its proximity to land, the convection became disrupted near the center; Tomas reweakened to a tropical storm near the Turks and Caicos Islands during a spell of moderate shear on November 6. After moving through that island nation, Tomas briefly became a hurricane for a final time before hostile wind shear from the nearby trough fully began to take effect. In conjunction with increasingly dry air, the cyclone steadily weakened to a tropical storm on November 7. Tomas lost its tropical characteristics the next day, though it retained gale-force winds as an extratropical cyclone. It turned sharply eastward before curving northward, accelerated by a broad cyclonic steering flow over the western Atlantic the next couple of days. Tomas' extratropical remnant subsequently raced off into the north Atlantic, until it was absorbed by another extratropical system a few hundred miles south of Newfoundland, Canada, on November 11.

Prior to the development of Tomas, the NHC noted the potential for heavy rainfall and strong wind gusts to spread across the Windward Islands, Venezuela, and northern Guyana, due to the tropical wave of which later developed into Hurricane Tomas. Upon development of Tropical Storm Tomas, most of the Windward Islands were put under a tropical storm warning, issued by their respective Governments; a tropical storm watch was also issued for Dominica. Six hours later as Tomas was nearly a hurricane, the tropical storm warning was replaced by a hurricane warning in Barbados, St. Vincent and the Grenadines, St. Lucia, and Martinique; the tropical storm watch in Dominica was also upgraded to a tropical storm warning.