Rainfall in Kottayam
Kottayam gets 51% of its rain from the monsoon, June to September, and June is its wettest month. In 2025 it got 2,243 mm, 2% above average (normal).
Month-wise rainfall in Kottayam
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 21 mm | 1% |
| February | 18 mm | 1% |
| March | 65 mm | 3% |
| April | 124 mm | 6% |
| May | 253 mm | 11% |
| June | 314 mm | 14% |
| July | 307 mm | 14% |
| August | 264 mm | 12% |
| September | 250 mm | 11% |
| October | 307 mm | 14% |
| November | 215 mm | 10% |
| December | 67 mm | 3% |
Yearly rainfall in Kottayam since 2006
Lighter bars are dry years, 20% or more below average (2012, 2016), when wells and borewells are drawn hardest.
What Kottayam'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 Kottayam sheds about 1,87,425 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 Kottayam?
About 2,205 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 2021 (3,176 mm) and the driest was 2012 (1,463 mm).
Which month gets the most rain in Kottayam?
June, with 314 mm in an average year, followed by July and October. February is the driest month (18 mm).
How much of Kottayam's rain falls in the monsoon?
51% of a normal year's rain falls from June to September. 10 months average 50 mm or more.
How much did it rain in Kottayam in 2025?
2,243 mm, which is 2% above the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in Kottayam increasing or decreasing?
It has held roughly steady: the last 10 years averaged within 5% of the 10 before them. Year-to-year swings are much bigger than the trend.
How much rainwater can a house in Kottayam harvest?
A 100 m² (about 1,076 sq ft) concrete roof in Kottayam sheds about 1,87,425 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 Kottayam district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.