The 2013 Pacific typhoon season was the most active Pacific typhoon season since 2004, as well as the deadliest since 1975. The season began with the formation of Severe Tropical Storm Sonamu on January 1; however, most of the first seventeen named storms before mid-September were relatively weak, as only two of them reached the typhoon strength. Typhoon Soulik in July was the strongest tropical cyclone to affect Taiwan in 2013. In August, Typhoon Utor cost US$2.6 billion damage and killed 97 people, becoming the second deadliest tropical cyclone of the Philippines in 2013. Three systems in August, Pewa, Unala and 03C, continuously crossed the International Date Line from the Central Pacific and entered this basin. The first two-thirds of the season were very weak, with only two typhoons forming despite the average amount of named storms forming. However, the season became dramatically active since mid-September. The last fourteen named storms formed within approximately two months, yet only three of them were below the typhoon strength. Initially, Typhoon Man-yi made landfall over Japan. Tropical Depression 18W, known in Vietnam as Tropical Storm No.8, flooding triggered by the storm in Vietnam, Laos and Thailand damaged nearly US$80 million and 23 deaths. Typhoon Usagi made landfall over Guangdong, China and cost US$4.6 billion in the country, which was the third strongest storm of the basin in 2013. Later, Typhoon Wutip made landfall over Vietnam. In early October, Typhoon Fitow made landfall over Fujian, China and caused over US$10 billion damage, becoming the costliest tropical cyclone in 2013. Typhoon Danas affected Japan and South Korea, but without significant damage. Typhoon Nari brought significant damage over the Philippines and eventually made landfall over Vietnam, as well as Typhoon Wipha which killed 41 people in Japan. Typhoon Francisco and Typhoon Lekima did not directly affect any country, but they were both violent typhoons, especially the latter one becoming the second strongest of this basin in 2013. Typhoon Krosa crossed northern Luzon on October 31 and intensified further, although it dissipated in the South China Sea. In early November, Tropical Depression Wilma formed over the Caroline Islands, moved out of the basin, and ultimately arrived in the Arabian Sea in mid-November. At the same time in early November, Typhoon Haiyan initially affected Palau significantly. The typhoon later became one of the most intense tropical cyclones on record and immediately made landfall over the Philippines. After arriving at the South China Sea, Haiyan made landfall over Vietnam and also impact Guangxi and Hainan provinces of China. Typhoon Haiyan, also known as Typhoon Yolanda, caused 6,300 fatalities and over US$2 billion damage in the Philippines, becoming the deadliest and costliest typhoon in modern Philippine history.