The state is wedged between the Lakshadweep Sea and the Western Ghats. Lying between north latitudes 8°18′ and 12°48′ and east longitudes 74°52′ and 77°22′,[93] Kerala experiences the humid equatorial tropic climate. The state has a coast of 590 km (370 mi)[94] and the width of the state varies between 11 and 121 kilometres (7 and 75 mi).[95] Geographically, Kerala can be divided into three climatically distinct regions: the eastern highlands; rugged and cool mountainous terrain, the central mid-lands; rolling hills, and the western lowlands; coastal plains.[96] The state is located at the extreme southern tip of the Indian subcontinentand lies near the centre of the Indian tectonic plate; hence, it is subject to comparatively low seismic and volcanic activity.[97] Pre-Cambrian and Pleistocene geological formations compose the bulk of Kerala’s terrain.[98][99] A catastrophic flood in Kerala in 1341 CE drastically modified its terrain and consequently affected its history; it also created a natural harbor for spice transport.[100] The eastern region of Kerala consists of high mountains, gorges and deep-cut valleys immediately west of the Western Ghats’ rain shadow.[96] 41 of Kerala’s west-flowing rivers,[101] and three of its east-flowing ones originate in this region.[102][103] The Western Ghats form a wall of mountains interrupted only near Palakkad; hence also known Palghat, where the Palakkad Gap breaks.[104] The Western Ghats rise on average to 1,500 m (4920 ft) above sea level,[105]while the highest peaks reach around 2,500 m (8200 ft).[106] Anamudi, the highest peak in south India, is at an elevation of 2,695 metres (8,842 ft).[107]

Kerala’s western coastal belt is relatively flat to the eastern region,[108] and is criss-crossed by a network of interconnected brackish canals, lakes, estuaries,[109] and rivers known as the Kerala Backwaters.[110] The state’s largest lake Vembanad, dominates the backwaters; it lies between Alappuzha and Kochi and is about 200 km2 (77 sq mi) in area.[111] Around eight percent of India’s waterways are found in Kerala.[112]Kerala’s forty-four rivers include the Periyar; 244 km, Bharathapuzha; 209 km, Pamba; 176 km, Chaliyar; 169 km, Kadalundipuzha; 130 km, Chalakudipuzha; 130 km, Valapattanam; 129 km and the Achankovil River; 128 km. The average length of the rivers is 64 km. Many of the rivers are small and entirely fed by monsoon rain.[113] As Kerala’s rivers are small and lacking in delta, they are more prone to environmental effects. The rivers face problems such as sand mining and pollution.[114] The state experiences several natural hazards like landslides, floods and droughts. The state was also affected by the 2004 Indian Ocean Tsunami.[115]

Climate[edit]

With around 120–140 rainy days per year,[116]:80 Kerala has a wet and maritime tropical climate influenced by the seasonal heavy rains of the southwest summer monsoon and northeast winter monsoon.[117] Around 65% of the rainfall occurs from June to August corresponding to the Southwest monsoon, and the rest from September to December corresponding to Northeast monsoon.[117] Southwest monsoon; The moisture-laden winds, on reaching the southernmost point of the Indian Peninsula, because of its topography, it divides into two branches; the “Arabian Sea Branch” and the “Bay of Bengal Branch”.[118] The “Arabian Sea Branch” of the Southwest monsoon first hits the Western Ghats in the state,[119] making Kerala the first state in India to receive rain from the Southwest monsoon.[120][121] Northeast monsoon: The distribution of pressure patterns is reversed during this season and the cold winds from North India pick up moisture from the Bay of Bengal and precipitate it in the east coast of peninsular India.[122][123] In Kerala, the influence of the Northeast monsoon is seen in southern districts only.[124] Kerala’s rainfall averages 2,923 mm (115 in) annually.[125] Some of Kerala’s drier lowland regions average only 1,250 mm (49 in); the mountains of eastern Idukki district receive more than 5,000 mm (197 in) of orographic precipitation: the highest in the state. In eastern Kerala, a drier tropical wet and dry climate prevails. During summer, the state is prone to gale force winds, storm surges, cyclone-related torrential downpours, occasional droughts, and rises in sea level.[126]:26, 46, 52 The mean daily temperatures range from 19.8 °C to 36.7 °C.[127] Mean annual temperatures range from 25.0–27.5 °C in the coastal lowlands to 20.0–22.5 °C in the eastern highlands.[126]:65

[hide]Climate data for Kerala
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °C (°F) 28.0
(82.4)
30
(86)
31
(88)
32
(90)
34
(93)
34
(93)
30
(86)
29
(84)
29
(84)
30
(86)
30
(86)
31
(88)
34
(93)
Average low °C (°F) 22
(72)
23
(73)
24
(75)
25
(77)
25
(77)
24
(75)
23
(73)
23
(73)
23
(73)
23
(73)
23
(73)
22
(72)
22
(72)
Average rainfall mm (inches) 8.7
(0.343)
14.7
(0.579)
30.4
(1.197)
109.5
(4.311)
239.8
(9.441)
649.8
(25.583)
726.1