Timeline of the 2009 Pacific typhoon season

This timeline documents all of the events of the 2009 Pacific typhoon season which was the period that tropical cyclones formed in the Western Pacific Ocean during 2009, with most of the tropical cyclones forming between May and November. The scope of this article is limited to the Pacific Ocean, north of the equator between 100°E and the International Date Line. Tropical storms that form in the entire Western Pacific basin are assigned a name by the Japan Meteorological Agency. Tropical depressions that form in this basin are given a number with a "W" suffix by the United States' Joint Typhoon Warning Center. In addition, 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. These names, however, are not in common use outside of the Philippines.

During the season, a total of 41 systems were designated as Tropical Depressions by either, the Japan Meteorological Agency (JMA), the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), the Joint Typhoon Warning Center (JTWC), or other National Meteorological and Hydrological Services such as the China Meteorological Administration and the Hong Kong Observatory. As they run the Regional Specialized Meteorological Centre for the Western Pacific, the JMA assigns names to Tropical Depressions should they intensify into a tropical storm. PAGASA also assign local names to tropical depressions which form within their area of responsibility; however, these names are not in common use outside of PAGASA’s area of responsibility.

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