Amid growing heatwaves, how India protects its heat-exposed populace 

Thresholds for different regions

Temperature thresholds for declaring heatwave conditions vary across plain, coastal, and hilly regions:  

Plain regions:  ≥40°C temperature

Coastal regions:  ≥37°C temperature 

Hilly regions: ≥30°C temperature

Departure from normal

A departure of 4.5°C – 6.4°C from the normal average temperature at any place is considered a heatwave condition, and a departure of more than 6.4°C is declared a severe heatwave.  

Actual maximum temperature (for plains only) 

If at least two stations in a Meteorological sub-division for at least two consecutive days record actual maximum temperature ≥ 45°C (heatwave) and ≥ 45°C (severe heatwave). 

Moreover, IMD issues colour-coded warnings based on the severity of the heatwaves. These are Green – No action needed; Yellow – stay updated; Orange – Be prepared. Red – Take action.

India’s vulnerability to heatwave conditions 

In India, heatwaves occur primarily from March to June, covering central, eastern, and northern Peninsular India. Prevalence of hot dry air, absence of moisture in the upper atmosphere, and cloudless skies are some of the factors providing favourable conditions for the development of heatwave-like conditions. 

The Intergovernmental Panel on Climate Change Sixth Assessment Report (AR6) also indicates that anthropogenic activities have compounded the frequency and intensity of extreme events since the 1950s. Global warming-induced heatwaves have become more frequent and severe in various parts of the world. 

India, located in the tropical region, is increasingly vulnerable to the growing heatwave conditions due to its high population density and large population size. As a developing country with a significant proportion of its workforce engaged in outdoor activities, its populace faces heightened exposure to extreme heat and its severe consequences. 

According to a 2022 report by the World Bank, about 75 per cent of India’s workforce (~ 380 million people) is involved in heat-exposed work. The heat waves can cause dehydration, heat cramps, heat exhaustion, heat stroke, anxiety, palpitations, nervousness, behavioural changes, and sometimes even death. The situation is further compounded by phenomena like urban heat island. 

Urban heat island: why cities are heating up 

An urban heat island is a temperature-induced phenomenon where a city or parts of a city experience much higher temperatures than nearby or surrounding areas. This is more pronounced at night when trapped heat during the daytime is released. 

Due to the urban heat island effect, various cities have experienced additional very warm nights per summer over the past decade. According to a study by the Council on Energy, Environment and Water, Mumbai recorded 15 additional very warm nights, Bengaluru 11, Bhopal and Jaipur 7 each, Delhi 6, and Chennai 4.

There are several factors behind this, including urban architecture, density, construction material used in building, roads, waste heat from vehicles and air conditioners, less open and green spaces, etc. As cities are expanding rapidly, in most cases through unplanned growth, the risk of urban heat islands will further increase. 

Impact on lives, livelihoods, and ecosystems 

The National Disaster Management Authority (NDMA) has termed heatwaves as the silent killer, as it caused an estimated 24,223 deaths across the country between 1992 and 2015. The National Crime Records Bureau (NCRB) recorded 3,798 deaths due to Heat/Sun Stroke during 2018-2022. 

Experts suggest that these heat wave-related official mortality counts in India are under-estimated and under-reported due to misclassification and sometimes focus on immediate causes rather than the underlying trigger. Most vulnerable to these are children, older persons, and people working in outdoor occupations such as construction workers, labourers, street vendors, police personnel, delivery persons, farmers, fishermen, etc.

Exposure to extreme heat affects human health, economic productivity, energy consumption, food and critical medical supplies. Other critical consequences include strain on water resources of arid and semi-arid regions, increased vulnerability to forest fires, high electricity demand, and physiological impacts on crops and livestock. 

Furthermore, it can change the sea-surface temperature, which, in turn, affects wind circulation patterns, frequency and severity of extreme events, and ecological changes related to fisheries and aquaculture. Hence, the government has taken various measures to mitigate the impact of heatwaves. 

Heat Action Plans and their effectiveness

In 2016, the National Disaster Management Authority (NDMA) issued ‘Guidelines for Preparation of Action Plan – Prevention and Management of Heat Wave’. It was revised in 2017 and in 2019. The NDMA is collaborating with 23 states to jointly implement Heat Action Plans (HAPs), which include early warning systems, awareness campaigns, public health responses, and setting up cooling centers. 

These HAPs serve as guiding documents for local authorities to take measures, prepare and respond to extreme heat events. The first such plan was launched by the Ahmedabad Municipal Corporation in 2013. Delhi also launched its Heat Action plan in 2024-25. 

In 2024, Uttar Pradesh State Disaster Management Authority (SDMA) was the first in the country to decide specific heatwave thresholds for all 75 of its districts. Such measures help state and district authorities to identify vulnerable areas, issue alerts, and implement specific mitigation and adaptation strategies. 

However, several structural challenges persist. There are only 12 disasters eligible for assistance under the National Disaster Response Fund (NDRF) and State Disaster Response Fund (SDRF). These disasters include cyclones, droughts, earthquakes, fires, floods, tsunamis, frost and cold waves. But heatwave is not listed among them. As a result, states are left with one-tenth of their SDRF share to spend on these ‘local disasters’, which is insufficient. 

In addition, concerns have been expressed over the effectiveness of HAPs. Many HAPs lack heat risk and vulnerability assessments. Analysis by the Sustainable Futures Collaborative suggests that cities tend to be more focused on short-term emergency measures than long-term solutions like increasing green and open spaces, rejuvenating waterbodies, etc. Hence, dependence on artificial cooling mechanisms is poised to increase.

Growing reliance on artificial cooling mechanisms

Air conditioners (ACs) are still a luxury in India, with less than 10 per cent of households owning it. Compared to this, AC penetration is more than 90 per cent in the US, about two-thirds in China, and one-third in Thailand. 

With increasing frequency of heatwaves, alongside rising per capita income and rapid urbanisation, AC penetration in India is also set to increase multifold in the coming years. However, this will have implications for energy demand and energy security. 

Cooling is no longer a luxury but a necessity, closely linked to health, well-being, economic growth, and the productivity of people. Therefore, the government launched the ‘India Cooling Action Plan’ in 2019. The plan aims to address the cooling requirements by reducing demand and promoting better technological options to enhance energy efficiency and provide access to sustainable cooling in the next 20 years (2017-18 to 2037-38). 

The ICAP is aligned with India’s commitments under the Kigali Amendment to the Montreal Protocol, which mandates a phased reduction in Hydrofluorocarbons (HFCs). India plans to implement this in four stages beginning in 2032: targeting a cumulative reduction of 10 per cent in 2032, 20 per cent in 2037, 30 per cent in 2042 and 85 per cent in 2047.

Need to ensure equitable access to cooling

Addressing India’s extreme heat challenge is crucial to sustain its economic development. This requires a multi-layered decentralised strategy. There is an urgent need to move from uniform thresholds (like 40°C for plains) to local heat vulnerability thresholds, supported by real-time vulnerability mapping. 

Accordingly, redesigning HAPs and notifying heatwaves as a disaster will help provide the required financial resources for effective implementation. In the long term, there is a need for planned urban expansion with mandatory green and open spaces, green roofs, reflective pavements, and rejuvenation efforts for urban water bodies. 

In an increasingly warming world, protecting India’s vast heat-exposed workforce and elderly population by ensuring equitable access to cooling needs to be a key policy priority. 

Post read questions

Discuss the geographical and climatic factors responsible for the increasing frequency and intensity of heatwaves in India.

Examine the role of the Urban Heat Island (UHI) effect in aggravating heatwave conditions in Indian cities.

Discuss the socio-economic vulnerabilities associated with heatwaves in India. Who are the most affected groups and why?

Critically evaluate the effectiveness of Heat Action Plans (HAPs) in India. Highlight the key gaps and suggest improvements. Discuss the role of early warning systems and local governance in mitigating the impact of heatwaves in India.

Evaluate the economic impacts of heatwaves with reference to productivity, energy demand, and agriculture.

(Abhinav Rai is a Doctoral candidate at the Department of Geography, Delhi School of Economics, University of Delhi.)

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