precipitation · India
Chennai, Tamil Nadu
October–December north-east monsoon total
Modelled demonstration series · not observed data
Chennai has run out of water and drowned within the same decade, which tells you the problem is storage and drainage rather than supply. A season this far above normal arrives on a city whose wetlands and flood plains have largely been built on. The water still goes where it always went; there are now houses there.
75 years, modelled
Same reading, two normals
| Normal | Mean | σ | Pct | Return |
|---|---|---|---|---|
| 1951–1980 | 800 mm | +2.10σ | 98th | 1 in 56 years |
| 1991–2020 | 867 mm | +1.73σ | 96th | 1 in 24 years |
Today would rank 6 of 76 for highest value in the modelled series. Nothing about the reading changes between rows — only the yardstick.
The season here
Chennai is one of the few Indian cities that gets most of its rain from the retreating north-east monsoon rather than the south-west one.
Where this series comes from
MODELLED SERIES — not observed. Parameters set from published Chennai north-east monsoon climatology; lognormal transform applied. The 75 annual values are synthesised by the seeded generator.
Every number on this page comes from a modelled series: 75 annual values synthesised by a seeded generator from published climatological parameters for Chennai, Tamil Nadu. It shows how anomaly reasoning works. It is not a measurement and must not be cited as one.
How to read σ
σ counts standard deviations from this place's own normal. The sigma guide · return periods.
More precipitation stations
Open Chennai on the field →