the Mekong River. The centre of the country is dominated by the predominantly flat Chao Phraya river valley, which runs into the Gulf of Thailand. Southern Thailand consists of the narrow Kra Isthmus that widens into the Malay Peninsula. Politically, there are six geographical regions which differ from the others in population, basic resources, natural features, and level of social and economic development. The diversity of the regions is the most pronounced attribute of Thailand's physical setting. The Chao Phraya and the Mekong River are the indispensable water courses of rural Thailand. Industrial scale production of crops use both rivers and their tributaries. The Gulf of Thailand covers and is fed by the Chao Phraya, Mae Klong, Bang Pakong, and Tapi Rivers. It contributes to the tourism sector owing to its clear shallow waters along the coasts in the southern region and the Kra Isthmus. The eastern shore of the Gulf of Thailand is an industrial centre of Thailand with the kingdom's premier deepwater port in Sattahip and its busiest commercial port, Laem Chabang. The Andaman Sea is a precious natural resource as it hosts popular and luxurious resorts. Phuket, Krabi, Ranong, Phang Nga and Trang, and their islands, all lay along the coasts of the Andaman Sea and, despite the 2004 tsunami, they remain a tourist magnet. Climate Thailand's climate is influenced by monsoon winds that have a seasonal character (the southwest and northeast monsoon). Most of the country is classified as Köppen's tropical savanna climate. The majority of the south as well as the eastern tip of the east have a tropical monsoon climate. Parts of the south also have a tropical rainforest climate. A year in Thailand is divided into three seasons. The first is the rainy or southwest monsoon season (mid–May to mid–October), which is caused by southwestern wind from the Indian Ocean. Rainfall is also contributed by Intertropical Convergence Zone (ITCZ) and tropical cyclones, with August and September being the wettest period of the year. The country receives a mean annual rainfall of . Winter or the northeast monsoon occurs from mid–October until mid–February. Most of Thailand experiences dry weather with mild temperatures. Summer or the pre–monsoon season runs from mid–February until mid–May. Due to their inland position and latitude, the north, northeast, central and eastern parts of Thailand experience a long period of warm weather, where temperatures can reach up to during March to