katabatic winds from blowing in, keeping the bulk of the Indian subcontinent warmer than most locations at similar latitudes. Simultaneously, the Thar Desert plays a role in attracting moisture-laden southwest summer monsoon winds that, between June and October, provide the majority of India's rainfall. Four major climatic groupings predominate, into which fall seven climatic zones that, as designated by experts, are defined on the basis of such traits as temperature and precipitation. Groupings are assigned codes (see chart) according to the Köppen climate classification system. Tropical wet A tropical rainy climate governs regions experiencing persistent warm or high temperatures, which normally do not fall below . India hosts two climatic subtypes- tropical monsoon climate, tropical wet and dry climate that fall under this group. 1) The most humid is the tropical wet climate—also known as tropical monsoon climate—that covers a strip of southwestern lowlands abutting the Malabar Coast, the Western Ghats, and southern Assam. India's two island territories, Lakshadweep and the Andaman and Nicobar Islands, are also subject to this climate. Characterised by moderate to high year-round temperatures, even in the foothills, its rainfall is seasonal but heavy—typically above per year. Most rainfall occurs between May and November; this moisture is enough to sustain lush forests, swampy areas and other vegetation for the rest of the mainly dry year. December to March are the driest months, when days with precipitation are rare. The heavy monsoon rains are responsible for the exceptional biodiversity of tropical wet forests in parts of these regions. 2) In India a tropical wet and dry climate is more common. Noticeably drier than areas with a tropical monsoon type of climate, it prevails over most of inland peninsular India except for a semi arid rain shadow east of the Western Ghats. Winter and early summer are long and dry periods with temperatures averaging above . Summer is exceedingly hot; temperatures in low-lying areas may exceed during May, leading to heat waves that can each kill hundreds of Indians. The rainy season lasts from June to September; annual rainfall averages between across the region. Once the dry northeast monsoon begins in September, most significant precipitation in India falls on Tamil Nadu and Puducherry leaving other states comparatively dry. The Ganges Delta lies mostly in the tropical wet climate zone: it receives between of rainfall each year in the western part, and in the eastern part. The coolest month