Moving slowly to the north, it steadily intensified, attaining hurricane intensity on October 18 near the Swan Islands.

The storm later made two landfalls on Cuba as it reached peak intensity with winds of 150 mph (240 km/h) and a minimum central pressure of 934 mbar (hPa; 27.58 inHg).

An open trough of low pressure was first observed off the eastern coast of Costa Rica in the southern Caribbean Sea on October 14.

By 2000 UTC on October 17, the disturbance attained a minimum central pressure of 993 mbar (hPa; 29.33 inHg),[2] with maximum sustained winds of 70 mph (110 km/h).

[3] At 0000 UTC on October 18, the tropical storm was analyzed to have attained hurricane strength in the vicinity of the Swan Islands as it began to move towards the north-northwest.

[3] The ship S.S. Atenas observed the hurricane at 1700 UTC later that day, reporting an eye associated with the storm and a minimum pressure of 974 mbar (hPa; 28.77 inHg).

[3] At the time, the storm was located in a region of relatively low barometric pressures, with an outermost closed isobar of 1009 mbar (hPa; 29.80 inHg).

[4] The major hurricane later made landfall on the Isla de la Juventud at 0800 UTC on October 20, with a minimum pressure of 939 mbar (hPa; 27.73 inHg) based on a report from Nueva Gerona.

The hurricane continued to intensify after crossing the island, reaching peak intensity at 1200 UTC later that day with maximum sustained wind speeds of 150 mph (240 km/h) and a minimum central pressure of 934 mbar (hPa; 27.58 inHg) prior to making landfall in western Cuba.

[2][3] Over Cuba, the storm slightly weakened prior to entering the Straits of Florida by October 21 with winds equivalent to a Category 3 hurricane.

A ship offshore the northern Cuban coast reported a minimum barometric pressure of 949 mbar (hPa; 28.03 inHg).

While in the straits, the hurricane began to accelerate to the northeast, passing 20–30 mi (30–50 km) in the vicinity of the Florida Keys and Biscayne Bay.

Barometers in Güira de Melena and Cojímar both recorded a barometric pressure of 939 mbar (hPa; 27.73 inHg) while located in the hurricane's eyewall.

[2] On Isla de la Juventud, a majority of homes and buildings were damaged or destroyed, including an 80-year-old church that withstood many hurricanes.

[2] A tidal wave overtopped the Malecón – a seawall built in 1900 by Leonard Wood to project the city – causing much of the damage.

Densely-population low-lying sections of the city were inundated,[6] with water reaching several meters high up to three to four streets inland.

[9] In the tourist section, the casino, jai alai buildings, and race track suffered only minor damage, though the bathing pavilion was demolished.

[11] In Quinta de Los Molinos, the National Horticultural Garden, which was said to have the largest variety of tropical plants in the world – was completely destroyed.

[12] While the storm was just offshore Cuba on early October 20, the Weather Bureau issued warnings in Florida for the approaching system.

[20] At Marsh Harbour a 20-foot-high (6.1 m) storm surge, accompanied by towering waves, carried homes up to 1 mi (1.6 km) landward.

An 8-foot-high (2.4 m) storm tide penetrated 1⁄4 mi (0.40 km) inland, and peak gusts were estimated as high as 150 mph (240 km/h).

On October 21, with the eye of the storm still 700 mi (1,130 km) from Bermuda, weather forecasts from the United States called for the hurricane to strike the island on the following morning with gale force.

[25][26][27] HMS Valerian, based at the HMD Bermuda, was returning from providing hurricane relief in the Bahamas and was overtaken by the storm shortly before she could make harbour.

She last radioed after sighting Gibb's Hill Lighthouse early in the morning, at which time the crew saw no sign of an approaching storm.

By the time she reached the Five Fathom Hole, conditions were too rough to risk the channel through the reefs and the crew were forced to turn southward to obtain sea room from the reefline, and heading directly into the storm.

[28] When the centre of the storm passed over Bermuda, winds increased to 114 mph (183 km/h) at Prospect Camp, whereupon the Army took down its anemometer to protect it.

Calcutta was tied (bow to the North) to the wall at the oiling wharf (at the northern end of the South Yard), where, during an unusually high tide, it was more exposed to the wind blowing eastward over the island, than it would have been in the more sheltered North Yard (where Capetown tore up two bollards but otherwise rode out the storm safely), so forty hawsers were used, but all snapped when the windspeed reached 138 mph (the highest speed recorded before the storm destroyed the dockyard's anemometer).

Both whalers and 3 Carley Floats lost") while she rode out the storm offshore, was instructed at 16:10 on the 22nd to attempt to contact Valerian, which had signalled "Am hove-to 5 miles south of Gibb's Hill" at 08:30 (and which had already gone down at 13:00).