2015 South Indian floods

Meteorological background

From October through December the northeast monsoon brings a significant portion of annual rainfall to southeastern India. In 2015, the seasonal pattern combined with a series of organized low‑pressure systems and depressions over the Bay of Bengal. These systems moved slowly along or onshore the Tamil Nadu coast, repeatedly delivering intense, concentrated rainfall in short periods. Local reports recorded very high 24‑hour totals — for example, around 370 mm at Ponneri and 266 mm at Chennai International Airport — with a particularly extreme 24‑hour amount of 490 mm recorded at Tambaram beginning 8:30 a.m. on 1 December.

Progression and key events

• 8 November: A low‑pressure area over the Bay of Bengal intensified into a depression, making landfall near the coast close to Puducherry and bringing heavy rain.
• Mid‑November: A well‑marked low‑pressure area tracked northward along the coast, producing very heavy rainfall on and near 15 November.
• Late November–early December: Additional systems developed and moved inland around 28–30 November and 1 December, renewing downpours and causing rivers, drains and reservoirs to overflow.

Impacts and human cost

The floods affected a wide swath of the coast from Chennai southwards to Cuddalore. Floodwaters inundated neighborhoods, cut communications and transport links, and forced mass evacuations. Official and media accounts indicated that more than 500 people lost their lives and over 1.8 million were displaced or required emergency shelter. Power outages and damaged roads impeded rescue and relief. Agricultural land and fisheries in coastal districts suffered severe losses, with many crops submerged and infrastructure for commerce and daily life badly affected.

Response and recovery

Local, state and national agencies coordinated search, rescue and relief operations, using military and civilian boats, helicopters and relief camps. Emergency supplies — food, clean water, medicines and temporary shelter — were distributed to affected populations. The floods prompted reviews of urban drainage, reservoir management and disaster preparedness in several cities, particularly in Tamil Nadu and around Chennai, where rapid urban expansion had increased runoff and strained stormwater systems.

Aftermath and lessons learned

In the months after the floods authorities worked on rehabilitation, rebuilding damaged infrastructure and strengthening flood‑management practices. The 2015 event highlighted the need for improved land‑use planning, better maintenance of waterways and reservoirs, and more resilient urban drainage and emergency response systems. It also underlined the vulnerability of low‑lying coastal communities to concentrated monsoon rainfall and the importance of timely weather warnings and coordinated evacuation plans in reducing loss of life.

For further regional context and official information, see sources covering the affected states and districts, including Andhra Pradesh, Tamil Nadu, and the union territory of Puducherry.