Climate
Indian climate is one system with a reversal in it: winds blow from sea to land in summer and land to sea in winter. Everything else — rainfall pattern, crop calendar, drought in Saurashtra and Kachchh — follows from that reversal and from where the two monsoon branches go.
Mental model
Treat the Indian monsoon as a giant sea-breeze on an annual clock, driven by one question: is the land hotter than the sea, or colder? Summer — land heats, low pressure over north-west India, winds blow from sea to land, rain. Winter — land cools, high pressure, winds blow land to sea, dry. Then add the two branches of the summer monsoon (Arabian Sea branch hitting the Western Ghats, Bay of Bengal branch deflected up the Ganga plain by the Himalayas) and the rainfall map of India draws itself: windward wet, leeward dry.
Associations
A short trigger on the left, everything it pulls with it on the right.
Two branches: Arabian Sea and Bay of Bengal.
The south-west monsoon splits at the tip of the peninsula. The Arabian Sea branch hits the Western Ghats and Gujarat; the Bay of Bengal branch is deflected by the Himalaya up the Ganga plain. Gujarat sits at the dry end of the Arabian branch, which is why rainfall falls off sharply from south Gujarat to Kachchh.
June in, September out, October turns around.
The south-west monsoon arrives around the start of June and withdraws through September. October to December is the retreating or north-east monsoon, which brings rain mainly to the Tamil Nadu coast, not to Gujarat.
Things to remember
The night-before list. Short enough to recall cold.
- 1Mawsynram and Cherrapunji in Meghalaya record the world's highest rainfall, caused by funnelling of the Bay of Bengal branch into the Khasi hills.
- 2Winter rain in north-west India comes from western disturbances originating over the Mediterranean, and it matters for the rabi wheat crop.
- 3El Niño years are typically associated with weaker Indian monsoon rainfall; La Niña years with stronger.
- 4Most of Gujarat falls in arid to semi-arid climate types; south Gujarat is markedly wetter than Saurashtra and Kachchh.
- 5The Arabian Sea is a cyclone basin too — Gujarat's long coast makes cyclone preparedness a standing state concern.
In detail
- India's climate is classified as tropical monsoon type, and the word 'monsoon' comes from the Arabic 'mausim', meaning season — referring to the seasonal reversal of wind direction.
- The south-west monsoon normally bursts over the Kerala coast around the first week of June and withdraws from the extreme north-west by about the end of September, giving most of India roughly three-quarters of its annual rainfall in these four months.
- Winter rainfall in Punjab, Haryana and western Uttar Pradesh comes from western disturbances — extra-tropical cyclones originating over the Mediterranean region and travelling east; this rain, called 'mahawat', is very valuable for the standing rabi wheat crop.
- Tamil Nadu's Coromandel coast gets most of its rain in October-December from the retreating (north-east) monsoon, because those land-origin winds pick up moisture while crossing the Bay of Bengal — which is why Tamil Nadu is dry when the rest of India is wet.
- Rainfall variability is extreme: Mawsynram and Cherrapunji in the Meghalaya hills are among the wettest places on earth, while parts of western Rajasthan and Ladakh receive very little rain — and as a rule, rainfall decreases as one moves from east to west across the Northern Plains.
- El Nino, the warming of the eastern Pacific off the South American coast, is associated with weak Indian monsoon years, while La Nina conditions are generally associated with good monsoon rainfall; the linked see-saw of air pressure between Tahiti and Darwin is called the Southern Oscillation.
Where people slip
- The north-east (retreating) monsoon waters Tamil Nadu, not Gujarat. An option giving Gujarat significant October-December monsoon rain is wrong.
Check yourself
Nothing here is scored — it will not change your mastery figures.
Winter rainfall in north-western India is mainly caused by:
From the question bank
India's climate is classified as which type under the Koeppen classification system, dominated by seasonal wind reversal?
From the question bank
The local hot, dry, dust-laden wind that blows over the Indo-Gangetic plains during the summer months, preceding the monsoon, is known as:
Books to read
- NCERT Class XI — India: Physical Environment
- NCERT Class IX — Contemporary India
- Certificate Physical and Human Geography by Goh Cheng Leong
Official sources
Hand-checked official domains only — the notes above carry no links of their own.