The Great Hurricane of 1780 killed approximately 20-30,000 in the Caribbean, hitting Barbados first on October 10. It is the Atlantic's deadliest recorded hurricane. From the article:
"Great Hurricane of 1780
In October 1780, a powerful storm slammed the islands of the Caribbean, killing more than 20,000 people. Known as the Great Hurricane of 1780, it is among the deadliest storms ever recorded. Specifics about the hurricane, such as its exact point of origin and strength, are unknown, as it took place before the advent of modern storm-tracking technology.
However, it is believed to have first made landfall in Barbados on October 10 before it swept through much of the rest of the eastern Caribbean over the next week. Barbados, Martinique and St. Lucia were among the locations hardest hit, and there were thousands of casualties on these islands, along with significant property damage.
Great Britain and France, both of whom were fighting in the American Revolutionary War (1775-83), had a number of warships in the Caribbean at the time of the storm. Sailors and naval vessels from both nations were lost in the hurricane.
Although there have been many deadly hurricanes in the years since 1780, only Hurricane Mitch in 1998, which left more than 11,000 people dead in Central America, has approached the Great Hurricane of 1780 in terms of lives lost."