historical boundary between Punjab and UP, and its flood plains provide fertile alluvial soil suitable for agriculture but are prone to recurrent floods. The Yamuna, a sacred river in Hinduism, is the only major river flowing through Delhi. The Hindon River separates Ghaziabad from the eastern part of Delhi. The Delhi ridge originates from the Aravalli Range in the south and encircles the west, northeast, and northwest parts of the city. It reaches a height of and is a dominant feature of the region. In addition to the wetlands formed by the Yamuna river, Delhi continues to retain over 500 ponds (wetlands < 5 ha), that in turn support considerable number of bird species. Delhi's ponds, despite experiencing ecological deterioration due to garbage dumping and concretization, supports the largest number of bird species known to be using ponds anywhere in the world. Existing policy in Delhi prevents the conversion of wetlands and, quite inadvertently, has led to the city's ponds becoming invaluable refugia for birds. The National Capital Territory of Delhi covers an area of , of which is designated rural, and urban therefore making it the largest city in terms of area in the country. It has a length of and a width of . Delhi is included in India's seismic zone-IV, indicating its vulnerability to major earthquakes. Climate Delhi features a dry-winter humid subtropical climate (Köppen Cwa) bordering a hot semi-arid climate (Köppen BSh). The warm season lasts from 21 March to 15 June with an average daily high temperature above . The hottest day of the year is 22 May, with an average high of and low of . The cold season lasts from 26 November to 9 February with an average daily high temperature below . The coldest day of the year is 4 January, with an average low of and high of . In early March, the wind direction changes from north-westerly to south-westerly. From April to October the weather is hot. The monsoon arrives at the end of June, along with an increase in humidity. The brief, mild winter starts in late November, peaks in January and heavy fog often occurs. Temperatures in Delhi usually range from , with the lowest and highest temperatures ever recorded being , respectively. However, was recorded at Mungeshpur on 15 May 2022 whereas one of the main weathering station, that is, Airport station recorded all time high of