Rainfall in Koch Bihar
Koch Bihar gets 73% of its rain from the monsoon, June to September, and July is its wettest month. In 2025 it got 2,525 mm, 10% above average (normal).
Month-wise rainfall in Koch Bihar
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 5 mm | 0% |
| February | 14 mm | 1% |
| March | 45 mm | 2% |
| April | 122 mm | 5% |
| May | 277 mm | 12% |
| June | 452 mm | 20% |
| July | 474 mm | 21% |
| August | 405 mm | 18% |
| September | 357 mm | 16% |
| October | 136 mm | 6% |
| November | 8 mm | 0% |
| December | 2 mm | 0% |
Yearly rainfall in Koch Bihar since 2006
Lighter bars are dry years, 20% or more below average (2006, 2007, 2008, 2012, 2014, 2015), when wells and borewells are drawn hardest. The last ten years averaged 55% more rain than the ten before.
What Koch Bihar'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 Koch Bihar sheds about 1,95,160 litres in an average year, most of it in four monsoon 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 Koch Bihar?
About 2,296 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 2020 (3,576 mm) and the driest was 2006 (1,440 mm).
Which month gets the most rain in Koch Bihar?
July, with 474 mm in an average year, followed by June and August. December is the driest month (2 mm).
How much of Koch Bihar's rain falls in the monsoon?
73% of a normal year's rain falls from June to September. 7 months average 50 mm or more.
How much did it rain in Koch Bihar in 2025?
2,525 mm, which is 10% above the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in Koch Bihar increasing or decreasing?
The last 10 years averaged 55% more rain than the 10 before them. Year-to-year swings are still bigger than that change.
How much rainwater can a house in Koch Bihar harvest?
A 100 m² (about 1,076 sq ft) concrete roof in Koch Bihar sheds about 1,95,160 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 Koch Bihar district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.