Heatwaves in India

Heatwaves are periods of abnormally high temperatures, often exceeding normal maximums, posing significant risks. In India, the India Meteorological Department (IMD) defines specific criteria for declaring a heatwave, based on actual maximum temperatures and their departure from normal. These events are primarily meteorological phenomena influenced by atmospheric circulation patterns and local conditions.

Heatwaves are a recurring extreme weather event in India with significant socio-economic and environmental impacts, including public health, agriculture, water resources, and energy demand. UPSC examines their causes, impacts, and disaster management strategies.

Heatwave (Plains)

Departure from normal temperature is 4.5°C to 6.4°C, OR actual maximum temperature is 45°C or more.

Severe Heatwave (Plains)

Departure from normal temperature is >6.4°C, OR actual maximum temperature is 47°C or more.

Heatwave (Hilly Regions)

Departure from normal temperature is 4.5°C to 6.4°C, OR actual maximum temperature is 37°C or more.

Severe Heatwave (Hilly Regions)

Departure from normal temperature is >6.4°C, OR actual maximum temperature is 39°C or more.

Causes of Heatwaves: Natural factors include atmospheric blocking, anticyclonic circulations, and the absence of moisture-laden winds. Anthropogenic factors like climate change contribute to increased frequency, intensity, and duration of heatwaves. Urban heat island effect, due to concrete surfaces and lack of green cover, exacerbates temperatures in cities.

Impacts of Heatwaves: Public health is severely affected, leading to heatstroke, dehydration, heat exhaustion, and increased mortality, especially among vulnerable populations like the elderly, children, and outdoor workers. Agriculture suffers from crop wilting, reduced yields, and livestock stress. Water resources are strained due to increased evaporation and demand. Energy demand surges for cooling, leading to power outages. Economic productivity declines due to reduced outdoor work capacity.

Nodal Agency

India Meteorological Department (IMD)

Primary Season

Pre-monsoon (April-June)

Vulnerable Regions

Indo-Gangetic plains, Central, Western, and Peninsular India

Health Risks

Heatstroke, dehydration, heat exhaustion, increased mortality

Climate Change Link

Increased frequency, intensity, and duration of heatwaves

Key Policy Framework

National Disaster Management Authority (NDMA) Guidelines for Heatwave

For UPSC Prelims, questions often focus on the IMD's definition of heatwaves and severe heatwaves, the geographical distribution of affected regions, the primary causes (both natural and anthropogenic), and the immediate health impacts. Knowledge of key government agencies involved in heatwave management (IMD, NDMA) is also crucial. Questions might also test the understanding of the urban heat island effect.

For UPSC Mains, the focus shifts to comprehensive analysis. Candidates are expected to discuss the multi-faceted impacts of heatwaves on public health, agriculture, water resources, and the economy. Disaster management strategies, including early warning systems, mitigation measures, and adaptation policies (e.g., Heat Action Plans), are important. The linkage between heatwaves and climate change, and India's preparedness and policy responses, are frequently examined, requiring a critical and holistic perspective.

• Definition of heatwave and severe heatwave by IMD (temperature thresholds, departure from normal).
• Geographical distribution of heatwave-prone regions across Northwest, Central, East, and Peninsular India.
• Major impacts on human health (heatstroke, dehydration), agriculture (crop loss), and water resources.
• Mitigation and adaptation strategies, including early warning systems and public awareness.
• Link between increasing frequency/intensity of heatwaves and climate change.

Heatwaves are a persistent and growing concern in India, with the IMD regularly issuing warnings for severe conditions across various states. Recent years have seen a noticeable increase in their frequency and intensity, highlighting the urgent need for robust preparedness and adaptation strategies.

The National Disaster Management Authority (NDMA) has issued comprehensive guidelines for the preparation of Heat Action Plans (HAPs) at state and district levels. These plans focus on early warning, public awareness, capacity building of health professionals, and inter-agency coordination.