1899 San Ciriaco hurricane
Hurricane San Ciriaco set many records on its path. Resulting in at least 3,369 deaths in Puerto Rico, the storm was the deadliest hurricane to hit the island and the strongest at the time, until the Hurricane San Felipe Segundo made landfall in 1928 as a Category 5 hurricane. It was also among the deadliest Atlantic hurricanes ever recorded.
1928 Okeechobee hurricane
While the storm was passing near Dominica, the San Juan, Puerto Rico Weather Bureau warned about the threat of the hurricane which would strike the island within a day or two. The advisory was sent via telegraph to 75 police districts and was broadcast from the naval radio station every two hours; this was the first hurricane warning broadcast by radio. Warnings were also posted for 12 ports along the southern coast, causing ships to avoid the island or remain at port. Effective preparation is credited for the relatively low death toll of 312, and not a single ship was lost at sea in the vicinity of Puerto Rico. By comparison, the weaker 1899 San Ciriaco hurricane killed approximately 3,000 people.