Skip to content
Rainfall · Tamil Nadu

Rainfall in Chengalpattu

1,297 mmof rain in an average year, 2006–2025

Chengalpattu gets 37% of its rain from the monsoon, June to September, and November is its wettest month. In 2025 it got 1,242 mm, 4% below average (normal).

Novemberwettest month, 320 mm on average
2021wettest year, 1,904 mm
2016driest year, 806 mm
8months a year with 50 mm of rain or more

Month-wise rainfall in Chengalpattu

Average rain in each month, 2006–2025.

0100200300400JanJan: 27 mmFebFeb: 6 mmMarMar: 20 mmAprApr: 20 mmMayMay: 59 mmJunJun: 81 mmJulJul: 108 mmAugAug: 146 mmSepSep: 139 mmOctOct: 225 mmNovNov: 320 mmDecDec: 146 mm
MonthAverage rainShare of the year
January27 mm2%
February6 mm0%
March20 mm2%
April20 mm2%
May59 mm5%
June81 mm6%
July108 mm8%
August146 mm11%
September139 mm11%
October225 mm17%
November320 mm25%
December146 mm11%

Yearly rainfall in Chengalpattu since 2006

Lighter bars are dry years, 20% or more below average (2012, 2013, 2016, 2018), when wells and borewells are drawn hardest.

050010001500200020062006: 1,197 mm2007: 1,224 mm2008: 1,465 mm20092009: 1,166 mm2010: 1,427 mm2011: 1,379 mm20122012: 1,018 mm2013: 1,023 mm2014: 1,119 mm20152015: 1,797 mm2016: 806 mm2017: 1,303 mm20182018: 926 mm2019: 1,182 mm2020: 1,549 mm20212021: 1,904 mm2022: 1,308 mm2023: 1,380 mm20242024: 1,521 mm2025: 1,242 mm- - average 1,297 mm

What Chengalpattu'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 Chengalpattu sheds about 1,10,245 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?

Water you can put back each year2,20,490 L≈ 22 water tankers of 10,000 L

1 mm of rain on 1 m² is 1 litre. The surface factor allows for water lost to splash, evaporation and first-flush.

Rainwater harvesting cost in ChengalpattuGroundwater level in Chengalpattu

Frequently asked questions

What is the average annual rainfall in Chengalpattu?

About 1,297 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 (1,904 mm) and the driest was 2016 (806 mm).

Which month gets the most rain in Chengalpattu?

November, with 320 mm in an average year, followed by October and August. February is the driest month (6 mm).

How much of Chengalpattu's rain falls in the monsoon?

37% of a normal year's rain falls from June to September. 8 months average 50 mm or more.

How much did it rain in Chengalpattu in 2025?

1,242 mm, which is 4% below the 2006–2025 average, or "normal" in the India Meteorological Department's terms.

Is rainfall in Chengalpattu 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 Chengalpattu harvest?

A 100 m² (about 1,076 sq ft) concrete roof in Chengalpattu sheds about 1,10,245 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 Chengalpattu district. It reads close to, but not exactly the same as, India Meteorological Department rain-gauge totals, and rain varies within a district.

Rainfall in other districts of Tamil Nadu