Most of the tropical cyclones of the 2013 Pacific typhoon season formed between May and November of that year. The scope of this article is the Pacific Ocean north of the equator, between 100°E and the International Date Line. Tropical storms which form in the Western Pacific basin are assigned a name by the Japan Meteorological Agency (JMA). Tropical depressions forming in this basin are given a number with a "W" suffix by the United States' Joint Typhoon Warning Center (JTWC). The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) assigns names to tropical cyclones (including tropical depressions) that enter or form in the Philippine area of responsibility, but these names are not in common use outside the Philippines. During the season, 51 systems were designated as tropical depressions by the JMA, the PAGASA, the JTWC or other national meteorological and hydrological services, such as the China Meteorological Administration and the Hong Kong Observatory. Since it runs the Regional Specialized Meteorological Centre for the western Pacific Ocean, the JMA assigns names to tropical depressions if they intensify into a tropical storm. PAGASA assigns local names to tropical depressions which form within its area of responsibility. During this season, 25 systems entered (or formed) in the Philippine area of responsibility; 11 made landfall over the Philippines. October was the most active month, with nine systems formed or active: eight typhoons and one weak storm. Three storms (Pewa, Unala and 03C) entered the Western Pacific basin in August. In early October and early November, two tropical depressions crossed the 100th meridian; one became Cyclone Phailin, the first cyclone since Cyclone Jal in 2010. Similar to October, in August 13 storms were counted by the JMA. Typhoon Haiyan underwent rapid intensification by nearly 100 millibars, the season's strongest storm; seven storms also underwent rapid intensification. The season tied the 1964 record for the largest number of tropical depressions. (en)