Rainfall in Sitamarhi
Sitamarhi gets 81% of its rain from the monsoon, June to September, and July is its wettest month. In 2025 it got 1,234 mm, 0% above average (normal).
Month-wise rainfall in Sitamarhi
Average rain in each month, 2006–2025.
| Month | Average rain | Share of the year |
|---|---|---|
| January | 6 mm | 0% |
| February | 13 mm | 1% |
| March | 22 mm | 2% |
| April | 26 mm | 2% |
| May | 97 mm | 8% |
| June | 186 mm | 15% |
| July | 313 mm | 25% |
| August | 284 mm | 23% |
| September | 220 mm | 18% |
| October | 60 mm | 5% |
| November | 1 mm | 0% |
| December | 3 mm | 0% |
Yearly rainfall in Sitamarhi since 2006
Lighter bars are dry years, 20% or more below average (2009, 2018), when wells and borewells are drawn hardest.
What Sitamarhi'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 Sitamarhi sheds about 1,04,720 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 Sitamarhi?
About 1,232 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 2008 (1,773 mm) and the driest was 2018 (768 mm).
Which month gets the most rain in Sitamarhi?
July, with 313 mm in an average year, followed by August and September. November is the driest month (1 mm).
How much of Sitamarhi's rain falls in the monsoon?
81% of a normal year's rain falls from June to September. 6 months average 50 mm or more.
How much did it rain in Sitamarhi in 2025?
1,234 mm, which is 0% above the 2006–2025 average, or "normal" in the India Meteorological Department's terms.
Is rainfall in Sitamarhi 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 Sitamarhi harvest?
A 100 m² (about 1,076 sq ft) concrete roof in Sitamarhi sheds about 1,04,720 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 Sitamarhi district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.