Chapter 3 — Climates of India

Weather is what we experience every hour or day — rain, sunshine, wind, and so on — and it keeps changing. Climate, on the other hand, is the pattern of weather that a region experiences over a long period of time, usually several decades. So while the weather in Delhi can be different on two consecutive days, Delhi's climate is described as subtropical with very hot summers and cold winters.

In many parts of India, the year is traditionally divided into six seasons called ṛitus: vasanta (spring), grīṣhma (summer), varṣhā (rainy season), śharad (autumn), hemanta (pre-winter), and śhiśhir (winter). Specific rituals and festivals — such as Vasanta Pañchamī and Śharad Pūrṇima — are associated with these seasons. Plants, animals, and human activities all change in rhythm with the ṛitus.

India has at least seven distinct climate types. The Himalayan mountains have an alpine climate with cold snowy winters. Lower hilly areas have a temperate climate, which is why many hill stations are located there. The northern plains have a subtropical climate with very hot summers and cold winters, where most of India's wheat is grown. The Thar Desert has an arid climate with extremely hot days and very little rainfall. The western coastal strip has a tropical wet climate good for rice and spices. The Deccan Plateau has a semi-arid climate, and eastern India and the southern peninsula experience a tropical climate with distinct wet and dry periods.

Five main factors shape a region's climate. Latitude determines how directly the sun's rays hit the surface — places near the Equator are warmer, those near the poles are colder. Altitude lowers the temperature as you go higher, which is why hill stations are cooler than the plains. Proximity to the sea moderates temperatures (Mumbai near the sea is milder than inland Nagpur). Winds can bring warm dry air from deserts or moist air from the ocean. Topography — the physical shape of the land — also matters; for example, the Himalayas shield India from cold Central Asian winds.

Monsoons form because land heats up and cools down faster than the ocean. In summer, the Asian landmass heats up and creates a powerful low-pressure system. Air always flows from high pressure to low pressure, so moist winds are drawn from the cooler, high-pressure ocean towards the hot land. This moisture condenses over the warmer land and falls as heavy monsoon rains. In winter the pattern reverses — the land cools faster, creating high pressure, so winds blow from land to ocean, bringing dry conditions to most of Asia.

The southwest monsoon is the summer monsoon. Winds blow from the southwest, carrying moisture from the ocean over India. The rains typically arrive at India's southern tip in early June and cover the entire subcontinent by mid-July. The northeast monsoon is the winter monsoon — winds reverse and blow from the land towards the ocean. These are mostly dry, but the portion that passes over the Bay of Bengal picks up some moisture and brings rainfall to parts of east and south India.

The key difference is that Mumbai lies near the sea, while Nagpur is far from the coast. The sea acts as a temperature moderator — it absorbs and releases heat slowly, keeping coastal areas from getting too hot in summer or too cold in winter. As a result, Mumbai's summer temperature is around 32°C, while Nagpur can reach up to 44°C. In winter, Mumbai stays around 18°C while Nagpur drops to about 10°C, giving Nagpur a temperature range of about 34°C compared to Mumbai's 14°C.

Mawsynram, located in Meghalaya, receives the highest average annual rainfall in the world — about 11,000 mm, which is the same as 11 metres.

A cyclone forms when a very intense low-pressure system develops near the sea, pulling in moist air from surrounding areas. As the winds collect moisture, they form clouds and rotate inwards towards the centre of the depression. This central area, which is cloudless, is called the 'eye of the cyclone'. The India Meteorological Department (IMD) tracks the formation, evolution, and likely landfall of cyclones, and the National Disaster Response Force (NDRF) responds to the damage they cause.

India's diverse weather patterns can lead to four main types of climate-related disasters. Cyclones are frequent on the eastern coastline and can destroy property, uproot trees, and cause soil erosion. Floods happen when heavy rainfall produces more run-off than the land can absorb, and states like Uttar Pradesh, Bihar, Kerala, Andhra Pradesh, and Assam are especially vulnerable. Landslides are common in hilly and mountainous states — Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh, and the Western Ghats — usually during the monsoon. Forest fires spread rapidly in states like Uttarakhand, Himachal Pradesh, Madhya Pradesh, and Chhattisgarh, harming wildlife and displacing communities.

Climate change refers to significant, long-term shifts in temperature, precipitation, and weather events — on a planetary or regional scale. While natural processes drove climate change in past millennia, since the 19th century it has been largely caused by human activities: burning fossil fuels (coal, petroleum, and natural gas), deforestation, harmful industrial practices, and excessive or wasteful consumption. These activities release large amounts of greenhouse gases that trap extra heat, causing rapid global warming. In India, early 2025 saw average temperatures 1 to 3°C above normal, resulting in a shorter and milder winter than usual.

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