The 1931 Atlantic hurricane season ran through the summer and the first half of fall in 1931. The 1931 season was average in terms of tropical cyclone formation, but below average in number of hurricanes. 13 tropical cyclones formed during the year, but only three reached hurricane status, and one reached major hurricane status. The season's only major hurricane, the 1931 Belize hurricane, was a Category 4 hurricane that caused severe devastation in Belize, killing approximately 2,500 people. The other hurricane of the season struck Puerto Rico and mainland Mexico as a Category 1 causing some moderate damage.
The first of many weak storms in 1931, this one developed in the western Caribbean. Wind speeds never rose above 45 mph (72 km/h). The storm moved on a nearly straight northwest track, eventually making landfall near Port Mansfield, Texas. The area experienced squally weather but was otherwise unaffected. Numerous waterspouts were spotted offshore, all spawned by the tropical cyclone.
Storm Two also formed in the western Caribbean. It moved inland near Chetumal, Mexico and turned northward through the Yucatan Peninsula. It reached its peak intensity of 70 mph (110 km/h) two days later, after reemerging into the Gulf of Mexico. Continuing northward, it weakened just before landfall in central Louisiana to 50 mph (80 km/h) sustained winds. Gale winds and heavy rains were reported, but no damage reports exist. The storm dissipated over Oklahoma.
The third storm of the season formed not far east of Martinique and tracked westward through the Caribbean, not gaining much intensity. It grazed the coast of Honduras and made landfall in central Belize. The storm briefly reemerged over the Bay of Campeche before moving into mainland Mexico and dissipating. Damage was minimal to non existent but it might have helped further saturate the area ahead of the catastrophic hurricane that would hit later in the season.
Another weak storm, this one never strengthened past minimal tropical storm intensity, and in fact, may have only been a tropical depression but the data was inconclusive. It formed northeast of Barbados and curved north-northwestward through the Lesser Antilles. It passed directly over Puerto Rico on August 17. Little else is written about the storm but it is likely the region received rain saturation that could have exacerbated the damage from the San Nicolas hurricane that September.
The 5th storm of the 1931 season remains the deadliest hurricane, and natural disaster, in Belize's history. It devastated the entire northern coast of the country. It formed east of the Barbados in early September and moved through the Caribbean, not strengthening much for the first four days of its life. On September 10, however, the storm began to rapidly intensify; going from a tropical storm to a Category 4 hurricane with 135 mph (217 km/h) winds in a very short period of time. September 10 is a national holiday in Belize, celebrating the defeat of the Spanish in the Battle of St. George's Caye much like Americans celebrate the Fourth of July. This, or its sudden intensification on the day of its landfall, perhaps increased the death toll. Belize City was nearly destroyed by the storm surge. As many as 2,500 people lost their lives in the hurricane. The storm then moved over the Bay of Campeche and made a second landfall near Veracruz and dissipated inland.
The second hurricane that season, Storm Six, also known as the San Nicolas Hurricane, formed a couple hundred miles east of the Leeward Islands on September 8 and took a nearly straight course for most of its lifetime. It strengthened into a hurricane while over the British Virgin Islands, briefly becoming a Category 2, weakening just before landfall in Puerto Rico. It struck the island only hours before Storm Five hit Belize. Due to the small size of the storm, damage was limited to a 5 or 6-mile (9.7 km) radius in the San Juan area. Two people were killed and damage was restricted to trees, windows, power lines and roofing. Storm Six weakened to a tropical storm and crossed over parts of Hispaniola and Jamaica and later made landfall near Majahual, Mexico. It regained hurricane status in the Bay of Campeche and made landfall near Veracruz. Gusts as high as 95 mph (153 km/h) were recorded in Veracruz. Apparently there was little damage to the city itself but several small boats were lost offshore and several sailors drowned. The 800-ton steamer Dos Equis sank with the loss of everyone on board. No exact figures exist. The storm quickly dissipated inland.
A tropical depression developed in the vicinity of the Bahamas on October 13. After strengthening into a tropical storm, the system accelerated northeastward and became extratropical east of Bermuda on October 16.
The tenth storm of the season formed in the western Caribbean on October 18 and took a nearly straight northeasterly track. Little is written of this storm in the Monthly Weather Review report, but according to the Best Track data, it crossed central Cuba the day after formation and trekked over the open Atlantic for the next three days. Wind speeds never exceeded 45 mph (72 km/h) and no damage reports exist.
A tropical depression developed in the southeastern Caribbean Sea on November 11. It moved northwestward and later strengthened into a tropical storm. The system made landfall in the Yucatan Peninsula, before dissipating over the Bay of Campeche on November 16.
The final storm of the season formed in late November north of the Leeward Islands. The storm moved northwestward over the western Atlantic before turning west-southwestward on November 24. It dissipated near the northern Bahamas.