Heatwaves in India Introduction 

• Heatwaves have become a recurring and intensifying climate phenomenon, both globally and in India. 
• As per the World Meteorological Organization (WMO), 2024 was the warmest year on record, with global temperatures about 1.55°C above pre-industrial levels. 
• India is witnessing an increasing frequency, duration, and intensity of heatwaves, which is a critical public health, economic, and equity challenge.
•  Similarly, Europe has been warmed at about twice the global average, as was highlighted in the 2024 European State of the Climate Report. 
  • The European State of Climate Report is an annual publication of Copernicus Climate Change Service, which is part of the European Commission.
  • It captures climate trends in Europe, and is published in collaboration with the World Meteorological Organisation.

What are heatwaves? How are they defined in India?

• • A heatwave is defined as a prolonged period of excessively hot weather that can cause serious health risks, damage the environment, and disrupt economic activities. In India, the India Meteorological Department (IMD) defines heatwaves based on specific criteria, which are essential in understanding and managing heat-related risks.

• Criteria for Heatwaves in India:

• Physiography of Regions:
  • Plains: A heatwave is declared when the maximum temperature recorded at a station reaches 40°C or more.
  • Coastal Areas: A heatwave is declared when the maximum temperature recorded at a station is 37°C or more.
  • Hills: A heatwave is declared when the maximum temperature recorded at a station is 30°C or more.
• Based on Departure from Normal Temperature:
  • Heat Wave: When the temperature departure from normal is between 4.5°C to 6.4°C.
  • Severe Heat Wave: When the temperature departure from normal is greater than 6.4°C.
• Based on Actual Maximum Temperature:
  • Heat Wave: When the actual maximum temperature reaches ≥ 45°C.
  • Severe Heat Wave: When the actual maximum temperature reaches ≥ 47°C.
• A heatwave is declared if these criteria are met in at least two stations in a meteorological subdivision for at least two consecutive days.

What is the Current Status of Heatwaves in India? 

• India has been experiencing intense heatwaves for decades, but in recent years, these events have become more frequent and severe, with significant impacts on human health and the environment. 
• Regions Most Affected by Heatwaves: Rajasthan, Gujarat, Uttar Pradesh, Delhi, Haryana, Punjab, and Madhya Pradesh are among the states that have been hit hardest by heatwaves. These areas experience extreme heat during the summer months, with temperatures often exceeding 45°C for several consecutive days.

Key Factors Causing Heatwaves 

• • Natural Causes of Heatwaves in India: Heatwaves in India are driven by both natural and human-induced factors, with several natural causes playing a significant role in the frequency and intensity of these extreme events. 

• High Atmospheric Pressure Systems: High atmospheric pressure systems are one of the primary natural causes of heatwaves. These systems trap warm air near the Earth’s surface and prevent the normal circulation of air masses. This leads to prolonged hot weather in regions affected by such systems, particularly during the summer months.

• Climate Variability: Climate variability, particularly natural climate phenomena such as El Niño and La Niña, plays a crucial role in shaping weather patterns across India. For instance, during El Niño events, warmer ocean temperatures in the Pacific Ocean disrupt atmospheric circulation, leading to hotter and drier conditions over much of the Indian subcontinent. These changes can cause increased frequency and intensity of heatwaves.

• Drought and Dry Conditions: Prolonged drought and dry conditions significantly exacerbate heatwaves. The absence of rainfall and moisture in the soil leads to quicker heating of the land during heatwaves, further intensifying the high temperatures. Areas with reduced moisture tend to experience much higher temperatures, as dry land heats up faster than moist soil.

• Changes in Wind Patterns: Shifts in wind patterns are another natural cause of heatwaves. These shifts can transport hot air from regions that typically do not experience extreme temperatures, intensifying heatwaves in areas that are not accustomed to such conditions. Changes in wind direction and strength are often linked to global climate shifts and the widening of atmospheric systems.

• Geography and Topography: Geographic features and topographical conditions can also contribute to heatwaves. Regions that are surrounded by mountains or are landlocked tend to trap hot air, leading to localized heat islands. These areas can experience significant temperature spikes compared to other regions.  Jaipur and parts of Churu in Rajasthan are examples of landlocked valleys that often trap hot air, resulting in temperatures that exceed 47°C during heatwaves. The mountainous terrain and lack of breeze contribute to these extreme conditions, causing intense heat for extended periods.

• • Human-Induced Causes of Heatwaves in India:
  • While natural causes contribute significantly to heatwaves, human activities, particularly global warming and urbanization, have intensified the frequency and severity of these extreme weather events. Below are the main human-induced causes:

• Global Warming: Global warming, primarily driven by human activities such as burning fossil fuels, deforestation, and industrial emissions, has significantly increased global temperatures. This long-term rise in Earth’s average temperature contributes to more frequent and intense heatwaves in India, as the global atmospheric system continues to warm.

• • • Example: Rajasthan, Uttar Pradesh, and Gujarat have experienced steadily rising average temperatures over the past few decades. For instance, Rajasthan’s capital, Jaipur, has seen a rise of 1.2°C in average temperatures from 1980 to 2010, leading to an increase in heatwave days. As a result, heatwaves have become more frequent and prolonged in these regions.

• Urban Heat Island Effect: Urbanization has exacerbated heatwaves, particularly in highly populated cities like Delhi, Mumbai, and Bangalore. The urban heat island effect occurs when urban areas experience higher temperatures than their rural surroundings due to factors such as extensive concrete, asphalt surfaces, and limited vegetation. These surfaces absorb and retain more heat, resulting in localized zones of higher temperatures.

• • • Example: In Delhi, temperatures can be 5-7°C higher than in surrounding rural areas due to the urban heat island effect. During June 2019, Delhi experienced a record-high temperature of 48°C, partly due to the dense concrete infrastructure and lack of green spaces in the city. This phenomenon not only makes heatwaves more intense but also increases energy consumption due to higher demand for air conditioning and cooling.

•  Heatwaves in Europe:

• • Proximity to the Arctic and Polar Amplification: Northern and eastern parts of Europe are geographically close to the rapidly warming Arctic region. The Arctic is experiencing warming at a rate three to four times higher than the global average, primarily due to albedo loss caused by melting ice. This phenomenon, known as polar amplification, significantly contributes to rising temperatures in Europe.
  • Cleaner Atmosphere and Decline in Aerosols: A decrease in air pollution has led to reduced aerosol concentrations in the atmosphere. With fewer aerosols to scatter sunlight, more solar radiation is directly absorbed by the Earth’s surface, resulting in higher temperatures.
  • Urban Growth and Heat Island Effect: Rapid urbanization across Europe, especially in densely populated cities, enhances the Urban Heat Island (UHI) effect. This intensifies local temperature increases and exacerbates the impacts of heatwaves.
  • Increasing Sea Surface Temperatures and Atmospheric Shifts: The surrounding seas of Europe are warming, influencing weather patterns. Changes in the jet stream and other atmospheric circulation systems are contributing to longer and more intense summer heatwaves.
  • Albedo Changes in Europe and the Arctic: As Arctic ice melts, darker land and ocean surfaces become exposed, absorbing more solar energy. This loss of reflective surfaces accelerates regional warming and reinforces heatwave trends across Europe.
  • Impact of Global Climate Change: Human-induced greenhouse gas emissions are pushing global temperatures closer to the 1.5°C limit. Land areas, particularly those in mid- and high-latitudes like Europe, are heating up faster than oceans, amplifying the heatwave intensity.
  • Temperature Rise in Europe: Since pre-industrial times, Europe’s average annual temperature has risen by 2.4°C, significantly higher than the global average increase of 1.3°C. The region has seen record-breaking heatwaves, such as the longest one recorded in Southeast Europe, and a noticeable decline in cold days.

Significance of Curtailing Heatwaves

• Boosting Economic Productivity: Around 75% of India’s workforce—approximately 380 million people—are employed in sectors vulnerable to high heat exposure, such as agriculture, construction, and transport. According to the International Labour Organization (ILO), heat stress could lead to annual GDP losses of 3–5% in countries like India. Implementing heat-mitigation strategies helps safeguard outdoor workers, minimize lost working hours, and maintain economic productivity across critical sectors.
• Promoting Social Equity and Justice: Heatwaves disproportionately affect vulnerable populations, including the poor, elderly, women, and migrant laborers. According to the National Disaster Management Authority (NDMA), over 1,000 deaths in India each year are directly linked to heat-related issues, often exacerbated by the lack of adequate protection and social support. Reducing the impact of extreme heat supports a more inclusive, people-centric approach to development, addressing social disparities and ensuring climate justice.
• Protecting Public Health: When ambient temperatures rise close to or beyond 37°C, the human body faces difficulty in dissipating internal heat, which can lead to heat stress and damage vital organs such as the brain, kidneys, and liver. A 2020 study showed that extreme heat events in India between 2000-2019 caused around 2,000 deaths annually due to heatstroke, dehydration, and organ failure. Hospital emergency units report 10–15% higher patient intake for heat-related illnesses during these periods. Effective heatwave mitigation strategies reduce the burden on hospitals and emergency services, improving overall healthcare system performance. 
• Combating the Urban Heat Island (UHI) Effect: The Urban Heat Island (UHI) effect leads to higher urban temperatures by 1–6°C compared to surrounding rural areas, worsening the demand for air conditioning and escalating energy consumption. According to the Indian Institute of Technology (IIT) Bombay, cities like Delhi and Mumbai experience UHI effects contributing to a 30% increase in energy consumption. Implementing strategies such as increasing green urban spaces and tree cover can help reduce UHI temperatures by 3–4°C, leading to a more sustainable and resilient urban environment. 
• Protecting Ecosystems and Reducing Environmental Stress: Prolonged heatwaves can stress ecosystems and endanger biodiversity. In India, rising temperatures have already resulted in a 15% decrease in agricultural productivity in several states, particularly in wheat and rice-growing regions. Moreover, studies by the Ministry of Environment, Forest, and Climate Change (MoEFCC) show that increasing temperatures threaten various species, pushing them toward extinction. Effective heat management is vital to preserving ecosystems and ensuring biodiversity for future generations. 
• Strengthening Climate Resilience and Advancing Sustainable Development Goals (SDGs): India has seen a 0.5°C increase in average temperatures between 1971 and 2019, leading to more frequent and severe heatwaves. The government’s National Action Plan on Climate Change (NAPCC) aims to reduce the impacts of climate change, focusing on adaptation strategies such as reducing the frequency of heatwaves. These actions contribute directly to SDG 13 (Climate Action), and India is aiming for a 30% reduction in carbon emissions by 2030, which will significantly impact climate resilience.

Key Challenges in Addressing Heatwaves in India

• Unpredictable and Early Onset of Heatwaves: Heatwaves are now arriving earlier than usual, leaving minimal time for preparation. In 2025, regions in North and Central India experienced intense heatwaves nearly 20 days earlier than in 2024, well before local Heat Action Plans (HAPs) could be implemented. This unpredictability hampers timely response and preparedness.
• High Exposure Among Informal Sector Workers: Approximately 75% of India’s workforce, nearly 380 million individuals, are employed in outdoor heat-prone jobs such as agriculture, construction, and street vending. In states like Odisha and Gujarat, many daily wage earners continued laboring during peak heat hours due to the absence of financial alternatives or workplace safety measures.
• Significant Economic and Productivity Losses: Heatwaves have a measurable economic impact. Estimates by the ILO and World Bank in 2023 indicate a potential loss of 3–5% of GDP and up to 6% of annual working hours. In high-exposure sectors like agriculture and construction, heat stress in states such as Rajasthan and Telangana led to reduced labor productivity and delays in infrastructure development.
• Disproportionate Impact on Vulnerable Communities: The effects of extreme heat are not felt equally. Marginalized populations—especially women, elderly citizens, migrants, and the urban poor—are more exposed and have limited coping mechanisms. In Delhi, migrant families residing in tin-roofed shelters during April 2024 faced extreme indoor temperatures, resulting in severe health complications.
• Gaps in Heat Action Plan Implementation: Although more than 140 cities and 23 states have adopted Heat Action Plans, many suffer from inadequate funding, limited coordination between departments, and lack of contextual adaptation. A 2023 study by CEEW revealed that only a few HAPs included critical features like cooling centers, local-language outreach, or integrated emergency responses.
• Low Public Awareness and Inadequate Risk Communication: Widespread lack of awareness regarding heatwave risks continues to be a major barrier, especially in rural and underserved urban regions. In Bihar, despite heatwave alerts issued by the IMD in 2024, numerous communities proceeded with outdoor weddings and public gatherings during peak heat hours, leading to a surge in heat-related illnesses.

Government Actions to Address Heatwaves

• Heat Action Plans: The government has developed Heat Action Plans across 23 states to improve heatwave preparedness. These plans involve early warnings, emergency response measures, and public health initiatives to help reduce the impact of heatwaves on human health and infrastructure.

• Example: Ahmedabad has been a pioneer in implementing heat action plans, and since the plan’s launch in 2013, the city has reduced heat-related deaths by 30%.

• Public Health Preparedness: The Union Ministry of Health periodically reviews heat-related illness preparedness, ensuring hospitals and healthcare workers are ready to respond swiftly to heat emergencies, such as heatstroke and dehydration.

• Example: The National Centre for Disease Control (NCDC) has provided guidelines for healthcare workers on handling heatstroke cases and preventing heat-related illnesses.

• Focus on Vulnerable Groups: The government prioritizes vulnerable populations, including children, pregnant women, the elderly, and individuals with chronic illnesses, by providing them with specific heat protection measures and public health initiatives.

• Example: During the 2019 heatwave, special cooling centers and water distribution points were set up in Delhi and Madhya Pradesh to protect vulnerable groups.

• Awareness Campaigns: Around 100 districts have initiated public awareness campaigns to educate citizens about the risks of heatwaves and provide guidance on heatwave safety measures such as hydration, appropriate clothing, and avoiding the sun.

• Example: Bihar launched a statewide campaign to educate the public about the importance of drinking fluids and staying cool during extreme heat, reaching over 1 million people.

Way Forward

• Effective Implementation of Heatwave Action Plans: States must play a leading role in effectively implementing heatwave action plans, working with other stakeholders such as local authorities, NGOs, and health professionals to ensure timely responses to heat-related risks.

• Sustainable Cooling Solutions: India must prioritize sustainable cooling solutions such as passive cooling technologies, including ventilated buildings, cool roofs, and the use of environmentally-friendly materials like porotherm bricks in construction. These solutions will help mitigate the urban heat island effect in cities. Delhi is focusing on promoting green rooftops in urban housing to combat the rising temperatures caused by urbanization.

• Heatwave Mitigation Plans: Comprehensive heatwave mitigation plans must include access to safe drinking water, oral rehydration solutions (ORS), shade structures in public spaces, and flexible working hours in workplaces, particularly in sectors like construction and agriculture.

• Adoption of Energy-Efficient Solutions: Encouraging the use of energy-efficient cooling solutions, such as desert coolers in dry areas, can significantly reduce energy consumption and alleviate the strain on power grids during heatwaves. The Gujarat Energy Development Agency (GEDA) promotes the use of desert coolers in rural and semi-urban areas to reduce dependence on air conditioning, thereby improving energy efficiency.

• Creation of More Green Spaces: Increasing urban greenery and tree plantation efforts can help reduce urban temperatures. According to the United Nations, investing US$ 100 million in street trees globally can reduce urban temperatures by 1°C.  The Haritha Haram project of the Telangana government aims to increase the green cover from 24% to 33%, which will help mitigate the effects of heatwaves in the state.