Hurricane San Ciriaco, also known as the 1899 Puerto Rico Hurricane, San Ciriaco Hurricane, or 1899 Hurricane San Ciriaco, was an intense and long-lived Atlantic Cape Verde-type hurricane which crossed Puerto Rico over the two day period August 8 to August 9, 1899. Many deaths occurred as a result, due to flooding. The cyclone kept tropical storm strength or higher for 28 days, which makes it the longest duration Atlantic hurricane on record and the second-longest anywhere in the world (behind Hurricane John in 1994).