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Extreme heat conditions in India are becoming more frequent with rising temperatures & humidity posing serious risks to health, economy & daily activities. Understanding how IMD defines, measures & issues heatwave warnings is crucial for preparedness & mitigation.
IMD declares a heatwave when temperatures in plains exceed 40°C, in hilly areas 30°C & in coastal regions when temperatures exceed 37°C with a 4.5°C deviation.
A heatwave is when temperature rises 4.5°C to 6.4°C above normal & severe heatwave occurs when increase is more than 6.4°C.
Heatwave thresholds vary based on historical temperature data what qualifies as a heatwave in Kerala may not in Odisha.
A heatwave is declared when at least two meteorological stations in a sub division record high temperatures for two consecutive days.
IMD uses surface observatories across India to track meteorological parameters & compare them against 1991-2020 temperature climatology.
High humidity & elevated night-time temperatures increase human discomfort as body struggles to cool down.
Typically occurs from March to June occasionally extending into July.
|
Category |
Temperature (Plains) |
Temperature (Hilly Regions) |
Coastal Areas |
|
Heatwave |
≥ 40°C & 4.5°C above normal |
≥ 30°C & 4.5°C above normal |
≥ 37°C with 4.5°C deviation |
|
Severe Heatwave |
> 45°C or 6.4°C above normal |
> 30°C with 6.4°C deviation |
NA |
|
Extreme Heatwave |
> 47°C |
NA |
NA |
Established: 1950
Headquarters: Geneva, Switzerland
Affiliation: United Nations (UN) specialized agency
Member Countries: 193
Standardization of Climate Data: Develops global definitions for heatwaves & other extreme weather conditions.
Climate Forecasting & Early Warning Systems: Works with national agencies to provide long term climate predictions & risk assessments.
Heat Health Warning Systems (HHWS): In collaboration with World Health Organization (WHO) WMO supports implementation of early warning systems to prevent heat related health risks.
Research & Climate Change Adaptation: Conducts studies on global warming trends, urban heat islands & increasing frequency of heatwaves.
Collaboration with Governments: Advises countries on heatwave preparedness, mitigation & resilience-building measures.
Global Framework for Climate Services (GFCS) – Helps governments develop climate informed policies.
WMO Regional Climate Centres (RCCs) – Assists in climate monitoring at regional levels particularly for heatwave predictions.
State of Global Climate Reports – Annual reports assessing temperature trends & heatwave frequency worldwide.
Established: 1875
Headquarters: New Delhi, India
Parent Organization: Ministry of Earth Sciences, Government of India
Weather Forecasting & Warnings: Issues daily, weekly & seasonal weather forecasts including heatwave alerts.
Heatwave Alerts & Color Codes:
Green: No heatwave
Yellow: Be aware (Heatwave conditions possible)
Orange: Be prepared (Severe heatwave expected)
Red: Take action (Extreme heat conditions)
Urban Heat Island Monitoring: Tracks rising temperatures in metro cities like Delhi, Mumbai & Chennai.
Collaboration with Disaster Management Authorities: Works with state governments for heatwave preparedness & response plans.
Heat Action Plans (HAPs) – In collaboration with National Disaster Management Authority (NDMA) provides guidelines to states on tackling heatwave risks.
National Framework for Climate Services (NFCS) – Supports better climate predictions & preparedness strategies.
Monsoon & Climate Research – Studies link between monsoon variations & extreme temperatures.
Established: 2005
Headquarters: New Delhi, India
Parent Organization: Ministry of Home Affairs, Government of India
Heatwave Risk Reduction & Preparedness: Develops guidelines for states on mitigating heatwave impacts.
Heat Action Plans (HAPs): Supports cities & states in implementing customized heatwave response strategies.
Public Awareness & Education: Runs campaigns on heatwave safety, hydration & first-aid measures.
Coordination with IMD & Health Departments: Helps in issuing alerts, medical preparedness & emergency response.
National Guidelines on Heatwave Management – Provides a framework for reducing mortality & economic losses due to heatwaves.
Cooling Action Plan – Promotes sustainable cooling solutions to combat rising temperatures in urban areas.
|
Category |
Impact |
|
Health |
Increases risk of heatstroke, dehydration, cardiovascular diseases & respiratory illnesses. Vulnerable populations include elderly, children & outdoor workers. |
|
Agriculture |
Reduces crop yields, damages standing crops & increases soil moisture loss, leading to droughts. |
|
Water Resources |
Leads to water shortages, depletes groundwater levels & reduces river flows. |
|
Energy |
Increases demand for electricity due to higher cooling needs, leading to power shortages & blackouts. |
|
Economy |
Affects labor productivity, disrupts outdoor work & impacts sectors like construction, tourism & agriculture. |
|
Biodiversity |
Causes heat stress in animals, reduces livestock productivity & increases risk of wildfires. |
For more information, please refer to IAS GYAN
Sources:
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PRACTICE QUESTION Q. Consider following statements regarding heatwaves in India:
Which of statements given above is/are correct? (a) 1 & 2 only Answer: (a) 1 & 2 only Explanation: Statement 1 is correct: A heatwave is declared in plains when maximum temperature crosses 45°C. Statement 2 is correct: In coastal areas heatwave can be declared even if temperature is 37°C provided it is 4.5°C above normal. Statement 3 is incorrect: A heatwave is declared on second day of high temperatures not three consecutive days. |
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