Rainfall in Dumka
Dumka gets 74% of its rain from the monsoon, June to September, and July is its wettest month. In 2025 it got 1,329 mm, 5% above average (normal).
Month-wise rainfall in Dumka
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 8 mm | 1% |
| February | 12 mm | 1% |
| March | 17 mm | 1% |
| April | 43 mm | 3% |
| May | 130 mm | 10% |
| June | 184 mm | 15% |
| July | 279 mm | 22% |
| August | 242 mm | 19% |
| September | 234 mm | 19% |
| October | 102 mm | 8% |
| November | 6 mm | 0% |
| December | 6 mm | 0% |
Yearly rainfall in Dumka since 2006
Lighter bars are dry years, 20% or more below average (2010), when wells and borewells are drawn hardest. The last ten years averaged 5% more rain than the ten before.
What Dumka'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 Dumka sheds about 1,07,270 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 Dumka?
About 1,262 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 2007 (1,529 mm) and the driest was 2010 (991 mm).
Which month gets the most rain in Dumka?
July, with 279 mm in an average year, followed by August and September. November is the driest month (6 mm).
How much of Dumka's rain falls in the monsoon?
74% of a normal year's rain falls from June to September. 6 months average 50 mm or more.
How much did it rain in Dumka in 2025?
1,329 mm, which is 5% above the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in Dumka increasing or decreasing?
The last 10 years averaged 5% more rain than the 10 before them. Year-to-year swings are still bigger than that change.
How much rainwater can a house in Dumka harvest?
A 100 m² (about 1,076 sq ft) concrete roof in Dumka sheds about 1,07,270 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 Dumka district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.