[20] The coastal districts of Andhra Pradesh usually bear the brunt of heavy rains that occur during the northeast monsoon; with numerous river systems and wetlands, Puducherry and eastern Tamil Nadu are prone to flooding.

[22] Several low-lying areas in Kanchipuram, including major thoroughfare Gandhi Road, were inundated as the city and its neighbourhood received a heavy precipitation of 340mm during the 24-hours that ended with 8.30 a.m. on 13 November 2015.

[29] The continued rains led to schools and colleges remaining closed across Puducherry and Chennai, Kancheepuram and Tiruvallur districts in Tamil Nadu, and fishermen were warned against sailing because of high waters and rough seas.

[34] The same day, Chief Minister of Tamil Nadu Jayalalithaa announced that, because of the continued flooding and rains, half-yearly school examinations originally scheduled for 7 December would be postponed until the first week in January.

[38] As intermittent rains returned, thousands of displaced residents from Chennai, Kancheepuram and Tiruvallur districts attempted to flee the stricken region by bus or train and travel to their family homes.

With the city slowly beginning to recover, state and national health officials remained watchful against disease outbreaks, warning that conditions were right for epidemics of water-borne illnesses to occur.

[49] Torrential rains inundated hundreds of acres of paddy fields in Thanjavur, Tiruvarur and Nagapattinam districts, and caused residential areas to flood by 8 December.

[1] On 25 April 2018, the skeleton of a man reported missing during the floods was discovered in the Chennai neighbourhood of Peerkankaranai near Tambaram, though a definitive identification could not be made immediately.

[17] All of the major auto- and truck-makers in the Oragadam and Sriperumbudur manufacturing belts resumed operations by 8 December, despite ongoing damage assessments; some employees were forced to continue working from their homes.

[95] Several Indian IT giants like Tata Consultancy Services and Wipro also informed their stakeholders about an expected material impact on its third-quarter earnings due to the floods and then to the low volume revenue during Christmas and New Year holidays in the west.

[97] Tamil Nadu Chief Minister Jayalalithaa announced an initial allocation of ₹5 billion (US$58 million) for relief and rehousing, with ₹400,000 (US$4,600) for each family who had lost relatives in the floods.

[115] Nine shipments of bedding, carpets, biscuits, rice and fresh water packets totalling ₹35 million (US$404,393) were despatched by lorry to Tiruvallur district on 5 December by state Environment Minister Thoppu N Venkatachalam.

For those living along the banks of the Adyar, Cooum River and the Buckingham Canal and who had lost homes, the Chief Minister ordered an immediate allocation of 10,000 tenements in Okkiyam Thoraipakkam and Perumbakkam, which had been built by the Tamil Nadu Slum Clearance Board.

[129][130][131] President Pranab Mukherjee said he was "saddened by the loss of human lives and serious damage to infrastructure in Chennai", stating his "prayers and good wishes are with the people of Tamil Nadu during this difficult time".

In the Lok Sabha, Parliamentary Affairs Minister M Venkaiah Naidu said that Singh would chair a high-level meeting to deliver relief to the people of Tamil Nadu.

"[88] On 18 November, Amit Shah, the national president of the Bharatiya Janata Party, stated the party would donate ₹10 million (US$115,541) towards flood-relief efforts in Tamil Nadu and also established a three-person commission to visit the state and report on the progress of the relief efforts with the delegation headed by Union minister Nirmala Sitharaman, accompanied by Union minister Pon Radhakrishnan and MP Gopal Chinayya Shetty.

[134] On 2 December, Rahul Gandhi, vice-president of the INC, expressed his concern via Twitter, stating his thoughts were with the people of Tamil Nadu, and urging Congress party workers in the affected regions to "extend all possible assistance".

Amrit Sangma, Caritas India communication officer, said the organisation would provide food, wash kits and clothes to affected people with the support of four local partners.

Celebrities such as RJ Balaji, actor Siddharth and Chinmayi actively participated in the relief process by using social media to co-ordinate aid and gather information.

[176] College students and corporate members were scheduled into a training regimen that consisted of survival skills, aquatic rescue, emergency medical response, relief warehousing, and essential-material transportation.

[183] Outside India, many members of the Indian and Tamil diaspora sent non-perishable food, clothes, bedding and relief funds from countries including Malaysia, Singapore, the UAE, Mexico and the United States.

[209] From 29 December 2015, the Tamil Nadu state government began a massive slum clearance programme, demolishing dozens of illegally constructed dwellings in the Saidapet area of Chennai.

Observing a monetary estimate for flood-related damages in the state could total "thousands of crores", the panel's recommendations included a crackdown on criminals involved in illegal construction, a swift removal of illegal encroachments from flood channels and riverbeds, the preparation of a calamity map of all important cities and including "standard vulnerability indices", and a continued level of high vigilance by central and state authorities, notably by the Home Affairs Ministry and the National Disaster Management Authority.

"[226] Sunita Narain, the director of the Centre for Science and Environment (CSE) think tank, said the unprecedented floods in the Chennai metropolitan region were the direct result of unregulated urbanisation.

[227] Media reports stated the Chennai Corporation had ignored September warnings of above-average monsoonal rains issued by the India Meteorological Department, and that extensive and costly projects begun in 2013 to desilt city storm drains had been ineffectively conducted.

Javadekar said the Inter-Governmental Panel on Climate Change (IPCC) and local assessments have indicated that extreme rainfall events will likely increase in frequency by the end of the 21st century.

At a subsequent press conference, Tamil Nadu Power Minister Natham Viswanathan and chief secretary Gnanadesikan claimed that relief and rescue work were in full swing and "extraordinary".

Following numerous complaints regarding the Tamil Nadu state government's lack of relief effort co-ordination, a public-interest litigation petition was filed in the Madras High Court; on 11 December, Chief Justice S.K.

"[234] A survey conducted in the worst-affected districts of Chennai by a group of volunteer organisations between 15 and 30 December found that most families had lost their sources of livelihood, and that the amount of financial assistance was insufficient.

[242] On 2 December, the government Press Information Bureau (PIB) released an edited photo showing the Prime Minister looking down from an aircraft window which was removed after criticism.