Rainfall in Idukki
Idukki gets 54% of its rain from the monsoon, June to September, and July is its wettest month. In 2025 it got 2,099 mm, 2% above average (normal).
Month-wise rainfall in Idukki
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 18 mm | 1% |
| February | 16 mm | 1% |
| March | 54 mm | 3% |
| April | 105 mm | 5% |
| May | 226 mm | 11% |
| June | 301 mm | 15% |
| July | 314 mm | 15% |
| August | 266 mm | 13% |
| September | 235 mm | 11% |
| October | 286 mm | 14% |
| November | 186 mm | 9% |
| December | 59 mm | 3% |
Yearly rainfall in Idukki since 2006
Lighter bars are dry years, 20% or more below average (2012, 2016), when wells and borewells are drawn hardest. The last ten years averaged 7% more rain than the ten before.
What Idukki'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 Idukki sheds about 1,75,525 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 Idukki?
About 2,065 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 (2,777 mm) and the driest was 2016 (1,352 mm).
Which month gets the most rain in Idukki?
July, with 314 mm in an average year, followed by June and October. February is the driest month (16 mm).
How much of Idukki's rain falls in the monsoon?
54% of a normal year's rain falls from June to September. 10 months average 50 mm or more.
How much did it rain in Idukki in 2025?
2,099 mm, which is 2% above the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in Idukki increasing or decreasing?
The last 10 years averaged 7% more rain than the 10 before them. Year-to-year swings are still bigger than that change.
How much rainwater can a house in Idukki harvest?
A 100 m² (about 1,076 sq ft) concrete roof in Idukki sheds about 1,75,525 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 Idukki district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.