Why in News

The India Meteorological Department (IMD) issued a severe heatwave warning for North and Central India for April 23–27, 2026, with temperatures projected at up to 44°C — 4–5°C above normal. East and West Uttar Pradesh are under “severe heatwave” alert; Vidarbha (Maharashtra) faces an “extreme heat warning.” The IMD’s April–June 2026 seasonal outlook warns of above-normal heatwave days across East, Central, Northwest, and parts of Peninsular India.

IMD’s Heatwave Definition

Technical Criteria

Area Heatwave Threshold Severe Heatwave
Plains ≥40°C AND ≥4.5°C above normal ≥6.4°C above normal
Hilly regions ≥30°C AND ≥4.5°C above normal ≥6.4°C above normal
Coastal regions ≥37°C AND ≥4.5°C above normal ≥6.4°C above normal

Alternatively: If actual maximum temperature ≥45°C on plains, it is declared a heatwave regardless of departure from normal.

IMD Alert System (Colour Codes)

Colour Meaning Action Required
Green No warning No action
Yellow Watch Be updated
Orange Alert Be prepared
Red Warning Take action

April 2026 Heatwave — Key Facts

Parameter Detail
Alert period April 23–27, 2026
Peak temperature Up to 44°C
Departure from normal 4–5°C above
Severe heatwave zone East/West Uttar Pradesh
Extreme heat warning Vidarbha, Maharashtra
Other affected areas Rajasthan, Madhya Pradesh, Bihar

Causes of India’s Heatwaves

Meteorological Causes

  1. Western disturbances absent in summer — these bring moisture to north India in winter; their absence allows dry, hot winds (loo) to dominate
  2. Loo winds — hot, dry westerly/northwesterly winds blowing from Pakistan/Rajasthan deserts
  3. Anti-cyclone conditions — high pressure traps heat near surface, prevents convection
  4. La Niña / ENSO influence — La Niña years correlate with hotter, drier conditions in India’s northwest
  5. Urban Heat Island (UHI) — urban surfaces absorb heat; cities 2–5°C hotter than surroundings

Climate Change Dimension

Trend Data
Heatwave frequency Increased by 1–2 additional events per decade
Heatwave intensity +0.3°C per decade in maximum temperatures
Heat-related deaths (2025) 4,419 (CSE State of India’s Environment 2026)
Wet-bulb temperature risk Rising humidity + heat creates “unsurvivable” conditions (>35°C wet-bulb)

Health Impacts of Heatwaves

Condition Description
Heat cramps Muscle spasms; early warning sign
Heat exhaustion Heavy sweating, weakness, cold/pale/clammy skin
Heat stroke Body temp >40°C; confusion; life-threatening emergency
Dehydration Kidney failure risk
Wet-bulb temperature Combines heat + humidity; >35°C wet-bulb = unsurvivable

Vulnerable populations: Outdoor workers, elderly, children, construction workers, farmers, urban slum dwellers.

Governance Response — Heat Action Plans

National Level

Body Role
IMD Forecast, alert issuance, colour-coded warnings
NDMA National Disaster Management Authority — SOP for heat emergencies
MoHFW Ministry of Health — hospital preparedness protocols
State governments Heat Action Plans (HAPs); cooling centres; ORS distribution

Ahmedabad Model

Ahmedabad’s Heat Action Plan (2013) — India’s first city-level HAP:

  • Colour-coded alert system linked to IMD forecasts
  • Pre-cooling hospitals and cooling centres
  • Public awareness campaigns
  • Result: 1,190 deaths prevented in 2015 heatwave (study showed 40% reduction)

Gaps

  • Only ~100 Indian cities have formal HAPs
  • Most HAPs untested in extreme events
  • Rural areas and construction workers poorly covered
  • No national Heat Act (unlike US or EU frameworks)

UPSC Relevance

Prelims

  • IMD heatwave definition: ≥40°C AND ≥4.5°C above normal (plains)
  • IMD colour codes: Green/Yellow/Orange/Red
  • Loo: Hot dry westerly wind in North India summers
  • Ahmedabad HAP: India’s first city-level Heat Action Plan (2013)
  • NDMA: National Disaster Management Authority

Mains

  • “India’s disaster management framework is ill-equipped for slow-onset climatic disasters like heatwaves. Critically examine.” (GS3)
  • Urban heat island effect — causes, impact, mitigation strategies

Facts Corner

Fact Detail
IMD heatwave threshold (plains) ≥40°C AND ≥4.5°C above normal
Severe heatwave ≥6.4°C above normal
April 2026 peak Up to 44°C; 4–5°C above normal
Worst affected East/West UP (severe); Vidarbha (extreme)
Heat deaths in India (2025) 4,419 (CSE report)
Ahmedabad HAP India’s first Heat Action Plan (2013)
Loo winds Hot, dry westerly winds in North India
Wet-bulb temperature >35°C = unsurvivable conditions