The Climate of Tamil Nadu, India is generally tropical and features fairly hot temperatures over the year except during the monsoon seasons. The city of Chennai lies on the thermal equator, which means Chennai and Tamil Nadu does not have that much temperature variation.

History

Under the Köppen climate classification the greater part of Tamil Nadu fills under Tropical savanna climate and smaller portions of the state fall under Humid subtropical climate; the climate of the state ranges from dry sub-humid to semi-arid.

Seasons

Summer The summer in Tamil Nadu runs throughout March, April and May and is characterized by intense heat and scant rainfall across the state.

Monsoon The state has three distinct periods of rainfall: advanced rainfall; rainfall from the tropical cyclones emerging in the neighbourhood of the Andaman Islands during the Retreat of Monsoons(October–November): and the North-East monsoon during the months of October–December, with dominant northeast monsoon winds from the western disturbances emerging over the Bay of Bengal. The dry season is from February to early June. Mid-June to December is the monsoon months.

Since the state is entirely dependent on rains for recharging its water resources, monsoon failures lead to acute water scarcity and severe droughts.

Tamil Nadu is classified into seven agro-climatic zones: north-east, north-west, west, southern, high rainfall, high altitude hilly, and Cauvery Delta (the most fertile agricultural zone).

Statistics Temperature + Average temperatures in various cities of Tamil Nadu (°C) — Winter(Jan – Feb) Summer(Mar – May) Monsoon(Jun – Sep) Post-monsoon(Oct – Dec) Year-round City Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec AvgChennai24 25 27 29 31 30 30 28 27 26 25 24 31Coimbatore 25 26 28 29 29 27 25 26 25 24 23 24 29Madurai25 27 29 31 32 30 29 28 27 25 24 25 32Tiruchirapalli 25 26 28 29 31 32 30 29 29 27 25 24 32

Precipitation + Average precipitation in various cities of Tamil Nadu (mm) — Winter(Jan – Feb) Summer(Mar – May) Monsoon 1(Jun – Sep) Monsoon 2(Oct – Dec) Year-round City Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec TotalChennai Coimbatore Madurai Tiruchirappalli

Weatherboxes

Desert Soil

Mostly, desert soils are seen around Madurai, Virudhunagar, Sivaganga, Ramanathapuram and some parts of Tirunelveli dist, a few adjoining districts. These districts are formally known as the desert districts of Tamil Nadu.

Disasters

Floods During the 2015 South Indian floods (most affected districts: Chennai, Kanchipuram and Cuddalore), Chennai received 1,049 mm (41.3 in) of rainfall in November, the highest recorded since November 1918 when 1,088 mm (42.8 in) of rainfall was recorded. The flooding in Chennai was described as the worst in a century.

Cyclones + List of Cyclones Hits Tamil Nadu Year Cyclone Formed Origin Highest winds Fatalities Missing Damages Sources 2010 Laila 17 May - 21 May 1400 km (865 mi) south of Kolkata in the Bay of Bengal 120 km/h 65 $117 million (2010 USD) Jal 01 Nov - 12 Nov 550km (340mi), to the southeast of Ho Chi Minh City, Vietnam 110 km/h 118 12 $1.73 billion (2010 USD) 2011 Thane 25 Dec - 31 Dec 1540km (960mi) to the east of Medan in Indonesia 140 km/h 48 - $235 million (2011 USD) 2012 Nilam 28 Oct - 01 Nov to the northeast of Trincomalee, Sri Lanka 95 km/h 75 $56.7 million (2012 USD) 2016 Nadah 29 Nov – 2 Dec extreme southeastern region of the Bay of Bengal 75 km/h 12 Vardah 6 Dec - 13 Dec near the Malay Peninsula and the south Andaman Sea 130 km/h 47 $3.38 billion (2016 USD) 2017 Ockhi 29 Nov - 6 Dec 425 km (265 mi) to the south-southeast of Colombo, Sri Lanka 155 km/h 318 141 $920 million (2017 USD) 2018 Gaja 10 Nov - 22 Nov near Gulf of Thailand 130 km/h 52 $775 million (2018 USD) 2020 Nivar 23 Nov - 27 Nov South of the Bay of Bengal 130 km/h 14 $600 million (2020 USD) Burevi 30 Nov - 5 Dec Off the coast of Aceh 85 km/h 11 6 2022 Mandous 6 Dec - 10 Dec South east of the Andaman Sea 100 km/h 9 $27.4 million (2022 USD) 2023 Michaung 1 Dec - 6 Dec South to the Andaman Sea 120 km/h 17 $1.32 billion (2023 USD) 2024 Fengal 25 Nov - 4 Dec Tropical low west of Sumatra, Indonesia 110 km/h 37 (20 in India, 17 in Sri Lanka) 50 $55 million (2024 USD) 2025 Ditwah 26 Nov - 4 Dec Offshore to the southeastern coast of Sri Lanka 75 km/h 647 183 $1.64 billion (2025 USD)

2004 Asian tsunami disaster

Drought & famine

Pollution

The air quality of industrial areas in Ennore, as well as in Poes Garden and Boat Club are above the standards prescribed by the environment ministry, according to a report by Coastal Resource Centre.

The centre took eleven air samples in and around North Chennai and Chennai city as part of their air quality study in Ennore 2016. 24-hour samples were taken using filters fitted to a low volume air sampler and analysed for PM 2.5 (Particulate Matter or dust less than 2.5 micrometres in size). The key documented sources of PM 2.5 pollution are automobile exhaust, burning of coal, burning garbage and landfill, smelting processing of metals.

Surprisingly, 10 out of the 11 air samples were between 1.4 and 3.7 times higher than prescribed by the Ministry of Environment, Forests and Climate Change. The quality of air in Nallathaneer Odai Kuppam in Ennore is the highest with 220 micrograms of particulate matter per cubic meter of air.

Other areas from Ennore include Manali with 156 ug/m3, Sivanpadaiveethi Kuppam with 156. 90 ug/m3 and Kodingayur with 154.90 ug/m3 which is all considered very unhealthy according to the US Environment Protection Agency.

The Ennore region has 3300 MW of installed coal power plant capacity, with more than 1500 acres as dedicated coal ash dumps, says the report.

Highlighting the health effects of bad air quality, Dr Hissamudin Papa, Founder and Director, HUMA Hospitals said, "We visited these areas in Ennore and found various health issues. Children who are 14 to 15 years old look like they are 8 years old. Women have hormonal issues and infertility. Many people have chronic obstructive pulmonary disease in these areas. The pollution needs to be reduced in these areas.

Even areas like Poes Garden and Boat Club ranged 104 and 101 UG/ M3 which is considered unhealthy according to US EPA standards. "The high concentration of polluting industries in the city’s northern and southern edges is affecting all of Chennai," said Dr Rakhal Gaitonde, a public health specialist.

According to the report by the Coastal Resource Centre, the level of manganese in eight of the eleven samples exceed the US EPA reference concentration for exposure to manganese. There are no standards in India for manganese in ambient air. Also, the levels of calcium silicon and crystalline silica, which are enriched in coal ash were found in the air samples.

"Manganese and nickel are well-known toxins and their effects are well-documented. Manganese is predominantly a neurotoxin, while nickel is a carcinogen. The measurement of such toxic substances from the rooftops of human settlements is indeed a cause of concern," added Dr Rakhal.

The Coastal Resource Centre wants the Tamil Nadu government to take immediate action to improve the air quality in Ennore. "The government needs to impose a moratorium on all industrial activities till the environment is restored, initiate long-term and continuous monitoring in Ennore region," said Nityanand Jayaraman, an environment activist.

He added, "No norms are followed by the Tamil Nadu Pollution Control Board. Why should people living in North Chennai have to bear all the harmful effects of the industries?"

The Coastal Resource Centre also wants the government to apprehend polluters and take corrective actions to bring the levels of dust and heavy metals in the dust below detection limits in residential areas.

See also Climate of India Climatic regions of India

References