For Tamil Nadu, peak summer traditionally ends in May. But this season, temperatures hovered around 40 degrees Celsius in many districts, bringing scorching conditions even into June, leaving residents to grapple with exhausting days and uncomfortably hot nights. Clearly, the time has come to move beyond seasonal, planned responses. It is against this backdrop that the state recently launched its Heat Action Plan 2026, introducing measures such as local heat vulnerability mapping, early warning systems and targeted interventions for vulnerable communities. Also, meteorologists are closely monitoring the tropical Pacific for the strengthening of El Niño, which could impact weather patterns, precipitation, and heat risks in the coming months. From outdoor workers and children to the elderly in dense urban areas, rising temperatures and heat stress are a true test of endurance for everyone.
Spending most of his day wandering the streets of Chennai to complete deliveries, platform-based gig worker Selvam says access to drinking water remains a challenge. “I am wary of drinking water from public kiosks so I carry a water bottle, but it runs out within an hour. I either request to refill it at the places where I deliver or depend on buttermilk distributed by residents and temples,” he said.
Meteorologists said May 2026 was significantly warmer than normal in many parts of Tamil Nadu and amid recent hot Mays, inland areas are facing persistent heatwave-like conditions. Regional Meteorological Center (RMC) observations indicate that Vellore recorded the season’s hottest temperature of 42.5 degrees Celsius on May 22, followed by Tiruttani and Meenambakkam in Chennai. The persistent heat caused moderate to severe heat-stress and increased restlessness in many districts, with temperatures reaching above 40 degrees during the last fortnight of May. RMC officials observed that the hot weather was due to strong pre-monsoon solar heating, dry continental air prevailing over the interior and delayed widespread southwest monsoon activity. The urban heat island (UHI) effect has further increased temperatures in densely populated areas.
sensitive interior districts
While factors such as inland location, limited influence of sea breeze and semi-arid conditions make the northern interior and central interior districts most sensitive to heat stress, the coastal urban Chennai Metropolitan Area (CMA) faces a distinct heat-related challenge due to high humidity and the UHI effect. A temperature of 37 °C with high humidity can be more stressful to the human body than 40 °C in dry conditions. Other meteorological factors, including cloudiness, increased humidity, and wind patterns, played a role in the warmer nights in coastal locations.
Heatwave-like conditions have become more frequent, longer-lasting and intense over the past decade in line with trends across India, says VR Durai, director of the Regional Weather Forecasting Centre, RMC, adding that interior districts like Salem, Erode, Tiruchi and Madurai are increasingly experiencing hot weather conditions with frequent days of temperatures above 40 degrees.
YEA Raj, former Deputy Director General of Meteorology, RMC, attributes the persistent heat in Tamil Nadu during June to strong westerly winds and low monsoon clouds, due to which high temperatures did not drop even at night at many places. When thunderstorm cloud activity is absent the rain-shadow state experiences intense heat. Heat stress depends on humidity levels which fluctuate throughout the day. Given similar high temperatures in Pamban and Madurai, the level of discomfort may vary according to humidity. He says the India Meteorological Department (IMD) observations are conducted in protected conditions, but people outside may feel higher temperatures, and dense population and traffic further aggravate the UHI effect.
Meteorologists say the combined effects of climate change, urbanization and natural climate variability have increased the likelihood of extreme heat events, underscoring the need for effective heat plans and early warning systems.
extreme heat events
According to the RMC, Tamil Nadu has witnessed a series of intense heat events over the past decade, with temperature records indicating a clear concentration of extreme heat in the north and interior districts. The most extreme heat events of the decade occurred between May 2017 and May 2024. The data shows that northern and interior Tamil Nadu remains the epicenter of extreme heat, while Vellore (which recorded the decade’s highest temperature of 43.7 degrees Celsius in May) has remained a major hotspot for the last decade. With more districts experiencing high temperatures and hot nights, heat is emerging as one of the significant meteorological hazards of the state.
Although temperatures in Tamil Nadu remained lower than Telangana, coastal Andhra Pradesh and north India, widespread 40-degree temperatures and high humidity added to the heat stress, especially on the coast. Intense heat wave conditions across Telangana led to 48 heat-related deaths. According to Mr. Durai, no deaths have been reported in Tamil Nadu.
Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather Services, said Banda in Uttar Pradesh emerged as one of the hottest places in the country this summer, with temperatures reaching 48.3 degrees Celsius and the temperature remaining above 47 degrees Celsius for several days. Interestingly, western Rajasthan, which is traditionally the hottest region of India during summer, did not see extreme temperatures this year. Instead, extreme heat remained concentrated over southwest Uttar Pradesh, parts of Madhya Pradesh, Marathwada and Vidarbha during May, he said.
IMD data shows that the average summer temperature in hot climate districts of Tamil Nadu has increased by about 0.5 °C to 0.9 °C over the last 35 years. Karur and Tiruchi show the steepest trend of temperature rise. Officials say even a small increase in average temperatures could substantially increase the frequency of hot days, hot nights and heat-stress conditions in such hotspots.
adverse weather events
According to RMC chief D. Shivanand Pai, the incidence of uncomfortably hot weather has increased in recent years due to global warming. The UHI effect contributed to the discomfort, creating a 4 to 5 °C difference in actual temperatures between urban and adjacent open areas. Land use and land cover changes are also triggers. Anomalies in sea surface temperatures in the tropical Pacific indicate a warming trend that may intensify by July. The Monsoon Mission Coupled Forecasting System suggests further strengthening of El Nino conditions during the southwest monsoon, potentially reaching moderate to strong intensity. This may affect the hot temperatures in Tamil Nadu in September. Its impact could extend through 2027, potentially leading to a warmer winter next year. Generally, it is associated with good northeast monsoon. However, Mr Pai says, each year is unique, and there have been some exceptions in the past.
Mr Palavat also believes that El Nino may not have any significant impact on Tamil Nadu and the south peninsular region this year. Its high impact will be visible in the rainfall patterns over central parts of India in August and September.
While much of the framework of heat governance revolves around outdoor temperatures and daytime heat, a recent study linking indoor temperatures and relative humidity in Chennai by Climate Trends, a research-based consultancy and capacity-building initiative, has found that residents face heat stress indoors even after the peak summer months. A continuous increase in night temperature was recorded. Indoor temperatures monitored in 50 houses in Chennai between October 2025 and April 2026 were found to frequently exceed 32 degrees Celsius and most of them experienced continuous heat for at least four months. Indoor temperatures peak between 8 pm and 9 pm, as concrete structures release heat accumulated throughout the day and night temperatures rarely fall below 31 °C. The study also found that structural characteristics of the dwelling, including building materials, played a decisive role in shaping indoor thermal conditions.
Heatwave in Tamil Nadu was notified as a state-specific disaster in 2024, facilitating the use of state disaster response funds for preparedness and relief. The notification also provided for compensation for heat-related deaths and paved the way for a coordinated response involving health, disaster management and local administration departments. Proposed relief measures include medical assistance and provision of oral rehydration salt and access to drinking water in affected areas.
Meanwhile, the impact of rising temperatures is being felt on all sectors. Outdoor workers, including construction and agricultural workers and street-vendors, face heat stress the most. A 2026 study, ‘Quantifying the impact of heat stress on labor productivity among informal outdoor workers in southern India’, was led by researchers including Vidya Venugopal, and published in the journal Scientific Reports (Nature Portfolio)Surveyed 1,560 outdoor workers in 11 districts of Tamil Nadu. It showed that prolonged exposure to high temperatures could impact workers’ productivity and health, increase the risk of dehydration and heat-related illnesses, and place additional pressure on public health systems. “During summer, I start work early. But, within a few hours, the heat starts overcoming me. I keep drinking water and take short breaks… By afternoon, I experience headache, fatigue and dizziness,” says R.Vimala, a construction worker in Sriperumbudur.
State Heating Action Plan
As part of efforts to strengthen preparedness, the State Heat Action Plan 2026 was launched by the Tamil Nadu State Disaster Management Authority and Tamil Nadu Disaster Risk Reduction Agency. It focuses on localized risk assessment by mapping localized heat vulnerability and developing an area-specific threshold mechanism, rather than relying solely on state-level averages. It aims to improve early warning systems, taluk-level heat limits and better coordination between government departments. Officials say daily district-level heat risk bulletins will be issued.
For workers, recommendations include rescheduling outdoor work and ensuring access to drinking water. In the health sector, the plan calls for increased surveillance of heat-related diseases and training of health workers. The agency has also sought feedback through https://beta-tnsmart.rimes.int/index.php/Action_plan/HeatWave.
Retired bureaucrat K. Phanindra Reddy says that in the short term, awareness should be created about the dangers posed by heatwaves and precautions to be taken, while the government takes measures to ensure supply of drinking water to the vulnerable population and mobilizes concerned departments to respond proactively in the event of a crisis. Restoration of water bodies and expansion of green cover should be long-term counter-measures.
The IMD plans to increase the use of heat indices and heat-stress monitoring instead of focusing on temperature alone. Apart from sharing annual climate reports with the Tamil Nadu government, it plans to include a heat index during specific hours to measure a realistic indication of thermal discomfort and ‘actually felt’ temperatures. However, activists point to persistent gaps between policy, planning and implementation. G. of Poovulagin Nanbergal. “There are enough scientific reports and action plans. But they remain only on paper,” says Sundararajan. He urged the government to address the UHI impact on a war footing by expanding urban green cover. One option is to transplant mature trees into cities. Their survival rate may initially be around 50%-60%, but this may improve with better management. While climate change is a global challenge, solutions must be tailored to local circumstances.
(Geeta Srimathi and Dennis S. With inputs from Jesudasan)
