Andaman and Nicobar Islands: Climate

The Andaman and Nicobar Islands are the first patch of Indian territory the monsoon touches every year. Rain reaches Port Blair around 20 May, ten to twelve days before it reaches Kerala.

Monsoon clouds building over Port Blair, Andaman. Photo by Ridhvan Sharma, via Wikimedia Commons, CC BY-SA 4.0.

Locator map of the Andaman and Nicobar Islands. Base map: India location map.svg, Wikimedia Commons (CC BY-SA 3.0); marker added.

mcqquestion.com

Indian Geography · IndGeo0121

The first Indian soil the monsoon touches.

20 May — earliest onset in India

Normal date the Southwest Monsoon reaches Port Blair, 10-12 days before Kerala.

Annual rainfall

3,000-3,500 mm

Varies by station, wettest May-December

Humidity

70-85%

Relative humidity, year-round

Temperature

22-31°C

Mean annual, around 26-27°C

Annual rainfall by station

Port Blair

3,180 mm

Mayabunder

3,300 mm

Car Nicobar

3,440 mm

Hut Bay

3,500 mm

Two monsoons, one archipelago

Southwest MonsoonLate May-Sep

Northeast MonsoonOct-Dec

Cyclone windowsApr-May & Oct-Dec

Dry stretchFeb-Mar only

⬇ Download as image

📑 Contents

1A Climate Fed by Two Monsoons
2Why Both Monsoons Reach the Islands
3Test Yourself
4Climate Extremes and Vulnerabilities
5Previous Year Question

🌴 A Climate Fed by Two Monsoons

1. A Humid Tropical Coastal Climate

Classification The Andaman and Nicobar Islands have a humid, tropical coastal climate. Meteorologists classify it as Koppen type Am, tropical monsoon.
Location The islands lie in the Bay of Bengal, roughly between 6°45′N and 13°41′N. That equatorial-tropical position drives the climate.
Temperature Daily temperatures rarely rise above 31°C or fall below 22°C. Mean annual temperature stays around 26-27°C, one of India's smallest seasonal ranges.
Humidity Relative humidity averages 70-85% through the year. It rarely drops below 60%, thanks to the surrounding sea.

2. Both Monsoons Bring Rain

Southwest Monsoon The Southwest Monsoon reaches the islands in late May. It stays active through September, with the heaviest rain in June.
Earliest in India Rain usually arrives over Port Blair around 20 May. That is the earliest monsoon onset anywhere in Indian territory, 10-12 days before it reaches Kerala.
Northeast Monsoon Unlike most of mainland India, the islands also get real rain from the Northeast Monsoon, October through December.
A Rare Pattern Most of mainland India dries out in winter, except Tamil Nadu's east coast. The Andaman and Nicobar Islands are the only other Indian region where the Northeast Monsoon brings significant rain.

🌊 Why Both Monsoons Reach the Islands

1. Three Reasons for the Dual-Monsoon Pattern

Equatorial Position The islands sit close to the equator. This lets the equatorial trough and the Inter-Tropical Convergence Zone reach them as it shifts with the seasons.
Warm Seas The Bay of Bengal around the islands stays above 28°C year-round. That keeps the air moist and unstable, ready to release rain.
Bay of Bengal Cyclones April-May and October-December are also peak cyclone windows here. Even when a cyclone's track misses the islands, its rainbands still bring heavy rain.

2. Rainfall Varies by Station and Season

Annual Total Annual rainfall ranges from about 3,000mm to 3,500mm, depending on the station.
Peak Months Peak rainfall runs from May through December, not December to May. Only February and March stay comparatively dry.
North vs South The northern Andamans peak with the Southwest Monsoon. The southern Nicobars peak slightly later, with the Northeast Monsoon.
By Station Port Blair averages about 3,180mm a year, wettest in June. Car Nicobar and Hut Bay average higher, around 3,440-3,500mm, wettest in November.

Test Yourself

⚠️ Climate Extremes and Vulnerabilities

1. Cyclones and a Changing Climate

Two Cyclone Windows The Bay of Bengal near the islands sees two cyclone seasons a year, April-May and October-December.
Warming Seas Sea-surface temperatures around the islands have risen about 0.7-0.9°C since 1950.
Coral Bleaching Marine heatwaves in 2016 and 2020 triggered coral bleaching events around the islands.
Sea-Level Rise As a low-lying archipelago, the islands are vulnerable to sea-level rise. It threatens coastal settlements and freshwater supplies.

2. Vegetation Shaped by the Climate

Forest Cover About 86% of the islands' land area is forested. That is the highest forest-cover share of any Indian state or Union Territory.
Forest Types High rainfall and humidity support tropical evergreen and semi-evergreen forests, similar to the Western Ghats and the Northeast.
Mangroves Mangrove forests cover roughly 600 sq km of estuaries and tidal creeks. They buffer the coast against storm surges.