Debby began as a tropical wave that collapsed shortly after leaving the coast of Africa. The wave travelled across the Atlantic, and became a tropical depression off the northern coast of Haiti on September 13. The depression turned north and strengthened into a tropical storm and then a hurricane. Hurricane Debby moved north-northeast, affecting Bermuda with tropical storm-force winds. It continued strengthening as it moved north, peaking at 135 mph (220 km/h). Tropical storm-force winds were also recorded at Cape Race in Newfoundland when Debby passed by on September 18. The storm began to speed up and weaken over the colder waters of the north Atlantic. Debby combined itself with a strong non-tropical system over the British Isles on September 20.