Mawsynram

Topic: Climate of India and the Monsoon · NCERT: Class 7, Ch 3 "Climates of India"; Class 11, Ch 4 "Climate"

Meaning

Mawsynram is a village on the crest of the Khasi hills in the East Khasi Hills district of Meghalaya (about 25°N). It gets the highest average yearly rainfall in the world, about 11,000 mm (NCERT). It matters because it shows how the shape of the land can turn a moist monsoon wind into extreme rain. UPSC often asks about it in place–feature and "which branch of the monsoon" questions.

Explanation

How the rain reaches Mawsynram (cause → process → result)

• Cause: the southwest monsoon (June–September).
• In May–June, north-west India heats up strongly and a deep thermal low forms there. A thermal low is an area of low air pressure made by heat.
• The thermal low pulls the southern trade winds across the equator.
• The Coriolis force (the turning effect of the Earth's spin) bends these winds to the right. They now blow from the south-west.

• The winds pick up a lot of moisture over the warm Bay of Bengal.

• Path: the Bay of Bengal branch.

• The Bay of Bengal branch first strikes the coast of Myanmar and south-east Bangladesh.
• The Arakan Hills in Myanmar turn a large part of it towards India.
• The wind enters West Bengal and Bangladesh from the south and south-east.

• A sub-branch strikes the Garo and Khasi hills of Meghalaya.

• Result: very heavy rain on the Khasi slopes.

• The Khasi hills stand in the path of the moist Bay wind.
• Funnel-shaped valleys squeeze the wind and force it upward.
• Rising air cools. Its water vapour condenses and falls as very heavy rain.

Why the rain is so heavy here: the conditions it needs

• A moist wind: the Bay of Bengal branch carries a lot of water vapour.
• Hills that face the wind: the Khasi hills block the wind, so the air must rise. This is orographic rain (rain caused when a mountain forces moist air to rise).
• Funnel-shaped land: the valleys narrow, so the air is pushed together and lifted even more strongly.
• Location on the crest: Mawsynram sits high on the side facing the wind (the windward side), where the lifting is strongest.

Mawsynram and its twin, Cherrapunji

• Cherrapunji (Sohra) is a town close to Mawsynram, on the same southern Khasi slopes.
• It is famous for historic rainfall records.

• Heavy rain has washed away its soil. So its surface is bare and rocky, and in places it is wet but has little vegetation.

• Today, Mawsynram holds the title of highest average yearly rainfall in the world.

Where it occurs

• Mawsynram: crest of the Khasi hills, East Khasi Hills district, Meghalaya, about 25°N.
• Cherrapunji (Sohra): close to Mawsynram, on the southern Khasi slopes, Meghalaya.
• Garo and Khasi hills (Meghalaya): struck by the sub-branch of the Bay of Bengal branch.
• Wider pattern of the Bay of Bengal branch:
• Brahmaputra valley: heavy rain in Assam and the north-east.

• Ganga plain up to Punjab: rain decreases from east to west as the air loses moisture inland.

• A similar windward effect elsewhere in India: the Western Ghats (Sahyadri) get 250–400 cm on their windward side from the Arabian Sea branch. Mawsynram's rain is far higher.

Don't confuse with

• Cherrapunji (Sohra): it is close to Mawsynram and is known for historic rainfall records. Mawsynram has the highest average yearly rainfall in the world. Both are in the Khasi hills of Meghalaya.
• Arabian Sea branch: it feeds the Western Ghats (250–400 cm on the windward side). Mawsynram is fed by the Bay of Bengal branch, not the Arabian Sea branch.
• Rain shadow area (Pune, Bengaluru): a dry zone on the leeward side (the side away from the wind), where sinking air warms and gives little rain. Mawsynram is the opposite case. It is on the windward crest, where rising air gives very heavy rain.
• Northeast monsoon (October–December): it gives the Coromandel coast of Tamil Nadu most of its rain (48%) [2]. Mawsynram's rain comes from the southwest monsoon (June–September).

Prelims Hooks

• Mawsynram is in the Khasi hills, East Khasi Hills district, Meghalaya. It is not in the Garo hills or in Assam.
• It gets the highest average yearly rainfall in the world, about 11,000 mm (NCERT).
• It is fed by the Bay of Bengal branch of the southwest monsoon. Trap: it is not fed by the Arabian Sea branch.
• Cause of the extreme rain: funnel-shaped valleys squeeze the moist Bay wind and force it upward (orographic rain).
• Cherrapunji (Sohra) is close by on the same southern Khasi slopes. It is known for historic records, and its surface is bare and rocky because heavy rain washed away the soil.
• The Arakan Hills (Myanmar) turn the Bay branch towards India, so it enters from the south and south-east.

Mains Points

• Relief controls where the rain falls:
• Hills that face the wind, such as the Khasi hills and the Western Ghats, force moist air to rise and get very heavy rain.
• Ranges parallel to the wind, such as the Aravallis, get little rain.

• Mawsynram is the extreme case: funnel-shaped valleys plus a windward crest give the world's highest average rainfall.

• High rainfall does not mean rich land:

• In Cherrapunji, very heavy rain has washed away the soil, leaving a bare, rocky surface with little vegetation in places.

• This shows that soil erosion on steep, rain-lashed slopes needs soil conservation and afforestation (GS-I and GS-III).

• Uneven monsoon rain in the north-east:

• Meghalaya holds the world rainfall record, yet the region's rain varies a lot from year to year.
• In 2025, East and northeast India got only 1,089.9 mm, the 2nd lowest since 1901 [3]. Over the same season, Northwest India got 127% of LPA (LPA, or Long Period Average, is the normal rainfall used as a baseline) [3].
• So water planning in the north-east cannot assume that heavy rain will always come.

Related concepts

• Southwest monsoon season
• Arabian Sea branch of the monsoon
• Rain shadow area
• Bay of Bengal branch of the monsoon
• Cherrapunji
• Dry Tamil Nadu coast in the southwest monsoon
• Break in the monsoon
• Monsoon depression

Read more

• The southwest monsoon season: the two branches, rain shadow and breaks