Rainfall in South Andaman
South Andaman gets 56% of its rain from the monsoon, June to September, and September is its wettest month. In 2025 it got 2,065 mm, 4% below average (normal).
Month-wise rainfall in South Andaman
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 51 mm | 2% |
| February | 22 mm | 1% |
| March | 42 mm | 2% |
| April | 79 mm | 4% |
| May | 255 mm | 12% |
| June | 310 mm | 14% |
| July | 297 mm | 14% |
| August | 268 mm | 12% |
| September | 328 mm | 15% |
| October | 191 mm | 9% |
| November | 189 mm | 9% |
| December | 132 mm | 6% |
Yearly rainfall in South Andaman since 2006
Lighter bars are dry years, 20% or more below average (2019, 2023), when wells and borewells are drawn hardest. The last ten years averaged 5% less rain than the ten before.
What South Andaman's rain is worth to a building
Every millimetre of rain on a square metre of roof is a litre of water. A 100 m² roof in South Andaman sheds about 1,83,685 litres in an average year, most of it in a few wet months. Sent into a recharge pit, it refills the ground instead of flooding the street.
Your building: how much can you recharge?
1 mm of rain on 1 m² is 1 litre. The surface factor allows for water lost to splash, evaporation and first-flush.
Frequently asked questions
What is the average annual rainfall in South Andaman?
About 2,161 mm a year, averaged over 2006–2025 from NASA POWER satellite and weather-model data for the centre of the district. The wettest year in that time was 2013 (2,639 mm) and the driest was 2023 (1,627 mm).
Which month gets the most rain in South Andaman?
September, with 328 mm in an average year, followed by June and July. February is the driest month (22 mm).
How much of South Andaman's rain falls in the monsoon?
56% of a normal year's rain falls from June to September. 10 months average 50 mm or more.
How much did it rain in South Andaman in 2025?
2,065 mm, which is 4% below the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in South Andaman increasing or decreasing?
The last 10 years averaged 5% less rain than the 10 before them. Year-to-year swings are still bigger than that change.
How much rainwater can a house in South Andaman harvest?
A 100 m² (about 1,076 sq ft) concrete roof in South Andaman sheds about 1,83,685 litres in an average year: area × rainfall × 0.85 for splash and evaporation. Sent into a recharge pit, that refills the ground under the house instead of running into the drain.
Rainfall from NASA POWER (bias-corrected satellite and weather-model rainfall) at the centre of South Andaman district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.