Rising Heatwaves in India

Context: In the backdrop of rising temperatures pointing towards a new climate normal, India must develop a comprehensive national heat strategy and embed it within its National Adaptation Plan ahead of the 30th UN Climate Change Conference (COP30) in Brazil in November 2025.

What are Heatwaves?  

• Heat waves are prolonged periods of excessively hot weather that can cause adverse impacts on human health, the environment, and the economy.
• Definition: In India, IMD defines heatwave based on the following criteria:
  • Physiography of regions:
    • Plains: The maximum temperature recorded at a station is 40 degrees Celsius or more.
    • Coasts: The maximum temperature recorded at a station is 37 degrees Celsius or more.
    • Hills: The maximum temperature recorded at a station is 30 degrees Celsius or more.
  • Based on departure from Normal Temperature:
    • Heat Wave: Departure from normal is 4.5°C to 6.4°C
    • Severe Heat Wave: Departure from normal is >6.4°C
  • Based on actual Maximum Temperature:
    • Heat Wave: When actual maximum temperature ≥ 45°C 
    • Severe Heat Wave: When actual maximum temperature ≥47°C
• Heat Wave is declared if above criteria are met in at least 2 stations in a Meteorological subdivision for at least two consecutive days.

Status of Heatwaves in India

• Early onset of Summer and rising Temperatures:
  • February, classified as ‘winter’ by the India Meteorological Department (IMD), recorded unusually high temperatures. E.g., Heatwaves were officially reported in Goa and Maharashtra by late February. Odisha, Telangana, and Maharashtra recorded temperatures exceeding 40°C.
  • 31 States and Union Territories experienced night temperatures at least 1°C above normal, while 22 States and UTs reported night temperatures 3°C to 5°C above normal. These anomalies indicate shifting climate patterns and rising global temperatures.
• Growing threat of Heatwaves:
  • Scientists have warned that global warming will lead to more frequent and intense heatwaves. According to IMD, between 1981 and 1990 there were 413 heatwave days in India. However, the heatwave days have increased to 600 days between 2011 and 2020.
  • Heatwaves also pose significant risks to public health, economy, and infrastructure. The number of deaths from heat-related causes increased from 5,457 between 1981 and 1990 to 11,555 between 2011 and 2020.

Factors behind the increase in Heatwaves in India

1. Natural Causes:

• High Atmospheric Pressure systems: Heatwaves occur when high-pressure systems stall over a region. These systems trap warm air near the Earth’s surface and prevent the normal movement of air masses, leading to prolonged periods of hot weather.
• Natural climate variations, such as El Nino and La Nina events, influence weather patterns and increase the likelihood of heatwaves. E.g., during El Nino events, warmer ocean waters in the tropical Pacific lead to changes in atmospheric circulation and weather patterns.
• Prolonged periods of drought and lack of precipitation reduces the overall moisture of the soil, causing the land to heat up more quickly during heat waves.
• Shifts in wind patterns transports hot air from one region to another which intensifies heat waves in areas that are not typically prone to such extreme temperatures.
• Geographic features and topographical conditions also contribute to the development of heat waves. For example, landlocked valleys and regions surrounded by mountains trap hot air and lead to temperature spikes.

2. Human-Induced Factors:

• Global Warming: The long-term increase in Earth’s average temperature, primarily driven by human activities such as burning fossil fuels, deforestation, and industrial processes, contributes to the frequency and intensity of heat waves.
• Urban Heat Island Effect: Urban areas with high population density, extensive concrete and asphalt surfaces, and limited vegetation tend to absorb and retain more heat, and have created localised zones of higher temperatures.

Steps taken by government to address Heatwaves: 

• Heat Action Plans: Government has updated Heat Action Plans across 23 states, aiming to strategically combat and manage heatwaves.
• Public Health Preparedness: Union Health Ministry reviews the preparedness for managing Heat-Related Illnesses (HRIs) periodically indicating a proactive approach to address the health impacts of heatwaves.
• Focus on Vulnerable Groups: Government initiatives prioritize protecting high-risk groups like children, pregnant women, the elderly, and people with chronic diseases.
• Awareness Campaigns: About 100 districts have initiated campaigns to raise awareness about heatwave risks and precautions.

Bottlenecks in Heatwave Strategies: 

• Inadequate Preparedness for Heatwaves: A study by the Sustainable Futures Collaborative analyzed heat preparedness in nine Indian cities and found:
  • No long-term heat adaptation strategies.
  • Reliance on short-term emergency responses such as:
    • Providing drinking water stations.
    • Adjusting work hours during peak heat.
    • Boosting hospital capacity for heat-related illnesses.
  • Lack of long-term interventions to protect vulnerable populations.
• Key Gaps in Heatwave Preparedness:
  • Limited access to cooling solutions for low-income and vulnerable groups.
  • No income protection for workers affected by extreme heat.
  • Inadequate fire management and electricity grid upgrades to handle increased cooling demands.
  • Poor urban heat monitoring and lack of heat island mapping.
  • Green cover and solar cooling efforts exist but are not targeted at high-risk populations.

Need for a National Heat Strategy: 

• India must develop a comprehensive National Heat Strategy as part of its National Adaptation Plan.
• This strategy should focus on:
  • Expanding weather monitoring systems.
  • Developing urban heat action plans.
  • Green infrastructure and sustainable cooling methods.
  • Ensuring social and financial safety nets for workers in heat-prone sectors.
• India should present a well-structured plan ahead of the 30th UN Climate Change Conference (COP30) in Brazil (November 2025).