Skies of Fury: Cyclones, Droughts, Heatwaves and Rare Winds

Atmospheric disasters are hazards born in the sky: tropical cyclones and their storm surges, slow-building droughts, intensifying heatwaves, and rare winds from cold waves to derechos. They span every timescale UPSC tests, from a cyclone that makes landfall in hours to a drought that unfolds over seasons, and they are the category where climate change is most visibly rewriting the odds: more Arabian Sea cyclones, hotter heatwaves, and flash droughts arriving in weeks instead of months.

This article covers the full atmospheric set: how cyclones form and are classified, what a storm surge is and why it kills, the four faces of drought, heatwaves and the Ahmedabad model that tamed them, and the cold waves and derechos at the edge of India's disaster map.

Cyclones: the rotating giants of the ocean

A cyclone is a weather system consisting of an area of low pressure in which winds circulate at speeds exceeding 61 km/h, also called a tropical storm. As Isaac Asimov wrote, nature's violence is most visible in tropical cyclones. A full-grown cyclone is a violent atmospheric whirl 150 to 1,000 km wide and 10 to 15 km tall, with a calm eye at the centre, a destructive eyewall around it, and spiral rainbands feeding it.

Five conditions must align for a cyclone to be born: a large sea surface warmer than about 26 to 27 degrees C to supply heat and moisture; the Coriolis force to impart spin (which is why cyclones do not form at the equator); small variations in vertical wind speed, meaning low wind shear so the vortex is not torn apart; a pre-existing weak low-pressure area; and upper-level divergence that vents rising air outward. The release of latent heat from condensing moisture is the engine that keeps the vortex alive.

India's exposure is severe. Its coastline of about 11,098 km, flat terrain, shallow continental shelf and dense coastal population make storm tides, high winds and heavy rainfall devastating. The North Indian Ocean sees only about 10 per cent of the world's tropical cyclones, yet 21 of the 23 deadliest cyclones in recorded history (each killing over 10,000 people) struck India and Bangladesh in the last 270 years, almost entirely because of intense storm surges. Thirteen coastal states and Union Territories, covering 84 districts, face cyclone risk, with Tamil Nadu, Andhra Pradesh, Odisha, West Bengal and Puducherry on the east coast and Gujarat on the west coast most vulnerable.

IMD classifies cyclonic disturbances by maximum sustained wind speed:

Two trends worry forecasters. First, Arabian Sea cyclones are rising: Nisarga (2020), Tauktae (2021) and Biparjoy (2023) mark a clear increase in severe storms on India's west coast, linked to warming seas. Second, rapid intensification is becoming common: warmer oceans let cyclones strengthen much faster, as Amphan did in 2020, shrinking the window for evacuation.

India's response is the most mature of any disaster system. IMD issues alerts through satellites, Doppler radars and numerical models with green-yellow-orange-red colour coding. The World Bank-supported National Cyclone Risk Mitigation Project (NCRMP), NDMA's flagship programme, built cyclone shelters, resilient infrastructure and evacuation routes across 8 coastal states (Phase-I in 2011 for Andhra Pradesh and Odisha at Rs 2,524.84 crore; Phase-II from 2015 to 2023 for six more states). Natural defences matter equally: mangrove plantations, shelterbelts and saline embankments blunt the wind and the sea. The payoff is Odisha: during Cyclone Fani (2019), the state evacuated over 1.2 million people within 24 hours with very few fatalities, a system of early warning, community preparedness and resilient infrastructure now treated as a global benchmark.

Storm surge: when the sea climbs ashore

A storm surge is the abnormal rise of seawater above the normal tide, pushed toward the coast by a cyclone's onshore winds and lifted by its low central pressure. It is not a wave and not a tsunami: it is the sea itself rising and flooding inland, sometimes several metres high and kilometres deep into the coast. Storm surge, or storm tide, is the single biggest killer in cyclones.

The Bay of Bengal is the world's most dangerous surge basin. Its shallow continental shelf, funnel-shaped coastline and low-lying deltas let the wind pile water far higher than in deep-ocean basins, which is why the deadliest cyclones in history cluster here. Cyclone Amphan (2020) drove surge flooding across West Bengal and Odisha; Cyclone Yaas (2021) did the same a year later. The historical lesson behind the statistic, 21 of the 23 deadliest cyclones hitting India and Bangladesh, is that wind destroys buildings but surge drowns populations.

Defence against surge is layered. Saline embankments hold back the sea at the shoreline; mangroves and coastal bio-shields absorb up to 66 per cent of cyclone wave energy (scaled up under the MISHTI mangrove initiative); the Integrated Coastal Zone Management framework and the CRZ Notification (2019) regulate what can be built where; and INCOIS issues storm-surge bulletins alongside its tsunami warnings, feeding into IMD's cyclone alerts so that evacuation orders account for the water, not just the wind.

Droughts: the slow-onset disaster

Drought is a prolonged deficiency of water, recognised as a disaster because of its vast expense, slow onset and lasting effect on vulnerable sections. The India Meteorological Department defines drought in any area where the rainfall deficiency reaches 26 per cent or more of the long-term normal. Unlike a flood, drought creeps: by the time it is declared, crops have already failed and wells have already dried.

Drought has four distinct faces, and mains answers must separate them:

The risk map is sobering. A 2024 Department of Science and Technology assessment found 91 districts in the very-high drought-risk zone and 188 in the high-risk zone, with over 60 per cent of districts prone to both floods and drought. New forms are appearing: flash droughts, where extreme heat depletes soil moisture in weeks rather than months, struck Marathwada in 2026. Natural causes include monsoon failure (as in 2009), El Nino events that suppress the monsoon (2015-16), and heatwaves that accelerate evaporation. Man-made drivers are deforestation, over-irrigation that crashes water tables (as in Punjab), and urbanisation that paves over recharge zones.

NDMA's guidelines build the institutional response: dedicated Drought Monitoring Cells in states, vulnerability maps for drought-prone regions, automatic weather stations for micro-level monitoring, an upgraded Drought Management Information System, watershed development with soil-moisture conservation, research on drought-resilient crops, and relief measures from fodder banks to community-based management through PRIs. The proven state models are Jalyukt Shivar in Maharashtra, the Mukhya Mantri Jal Swavalamban Abhiyan in Rajasthan, Mission Kakatiya in Telangana and Sujalam Sufalam in Gujarat, all built on watershed restoration and water harvesting.

The forward agenda is to move from managing droughts to managing risk: NAQUIM 2.0 brings aquifer mapping down to the panchayat level for precision groundwater management, over 68,000 ponds were completed under Mission Amrit Sarovar by March 2025, the Pradhan Mantri Krishi Sinchayee Yojana expands efficient irrigation, and AI-based predictive analytics is being piloted so that India's agrarian economy is no longer, in the old phrase, a gamble on the monsoon.

Heatwaves: India's new health emergency

A heatwave is a period of unusually high temperatures lasting several days. The World Meteorological Organization defines it as daily maximum temperatures exceeding the local average maximum by 5 degrees C or more for at least five consecutive days. IMD operationalises it for India: a heatwave is declared when the maximum reaches at least 40 degrees C in the plains (30 degrees C in hills) with a departure of 4.5 to 6.4 degrees C from normal, or 45 degrees C regardless of normal; beyond 6.4 degrees of departure or 47 degrees C, it is a severe heatwave.

The numbers mark heat as a national emergency. A CEEW study found about 57 per cent of Indian districts, home to 76 per cent of the population, at high to very high heat risk. Heatwaves form under high-pressure anticyclones, where descending air compresses and warms (adiabatic heating), aided by hot dry air masses, cloudless skies and absent upper-atmosphere moisture. Cities amplify it: the urban heat island keeps places like Delhi and Bhubaneswar up to 1.22 degrees C warmer than their rural surroundings at night, and climate change is steadily raising both frequency and intensity.

The impacts are multidimensional: dehydration and fatal heatstroke (extreme heat now threatens India's 15 million gig workers), drying of rivers and reservoirs, power-demand surges that strain the grid, crop losses from heat stress, livestock distress, and more forest fires. NDMA's guidelines answer with early warning from IMD forecasts, health-sector preparedness with ORS and cooling aids, rescheduling of outdoor and MGNREGA labour away from the 12 to 3 pm peak, public cooling shelters, and cool-roof policies.

The institutional model is the Heat Action Plan (HAP), a pre-emptive city strategy combining early warning, inter-departmental coordination, public awareness and health-system readiness. The Ahmedabad HAP of 2013 was India's first city-level plan and is treated as the model for others; Odisha followed with a state-level HAP; and by 2024, 23 states had adopted NDMA-based heatwave management plans. The direction now is anticipatory action: cool roofs, urban water bodies as heat sinks (Odisha's Ama Pokhari and the Amrit Sarovar missions), and heat-risk atlases guiding city planning toward a heat-resilient future.

Cold waves and derechos: the other atmospheric extremes

A cold wave is a sharp, sustained fall in temperature. IMD declares one in the plains when the minimum temperature drops to 10 degrees C or less (0 degrees C or less in hilly regions); the WMO definition is a marked fall in maximum, minimum and average temperatures over a large area persisting for at least two consecutive days. Cold waves are among India's deadliest weather hazards: over 4,700 deaths between 2001 and 2019 and another 2,900 between 2019 and 2022.

The causes are a winter machine: chilled air masses flowing in from Central Asia and Siberia, La Nina conditions that intensify North Indian winters, clear skies that let the earth radiate heat away at night, high-pressure systems trapping cold air near the surface, western disturbances whose passage is followed by sharp cooling, and the Himalayan barrier itself, which blocks warm southern winds and traps cold air over the Indo-Gangetic plains in a cold bowl. IMD records a roughly 1.6-fold increase in cold-wave days over the last decade, though patterns are shifting: October to December 2025 saw 49 cold-wave days (a five-year high), while winter 2025-26, under La Nina, brought an unusually intense cold wave.

The damage spreads across health (hypothermia, strokes and heart attacks, as in Kanpur in January 2023 where 98 deaths were cold-linked), agriculture (ground frost damaged 15 per cent of the mustard crop in Shekhawati and Punjab in 2025), transport (dense fog disrupting rail, road and air), energy demand spikes, and severe hardship for the homeless and daily-wage workers. NDMA's 2021 guidelines on cold waves and frost push shelter homes, health-system readiness and advisories for vulnerable groups.

A derecho (from the Spanish la derecha, meaning straight) is a widespread, long-lived straight-line windstorm associated with a band of rapidly moving thunderstorms. Unlike a tornado, its winds do not rotate; unlike a hurricane, it is not a vortex at all. NOAA's criteria: a wind-damage swath extending more than 400 km, with gusts of at least 93 km/h along most of its length. It is a warm-weather phenomenon, mostly June to July, in three forms, progressive, serial and hybrid, and its severe storms can turn the sky green as light interacts with the huge water content of the clouds.

In India, derechos are rare and not formally classified as a disaster. There is no dedicated derecho mechanism; they are handled through IMD's thunderstorm, squall and high-wind nowcasts issued via Doppler radar, SMS, the Damini lightning app and the Mausam app. For UPSC, the derecho is a classic prelims fact: definition, the 93 km/h and 400 km thresholds, the straight-line versus rotating distinction from tornadoes, and the warm-season timing.

Dust storms: the andhi of the northwest

Every pre-monsoon season, northwest India braces for the andhi, the violent dust storm that sweeps across Rajasthan, Punjab, Haryana, Delhi and western Uttar Pradesh. A dust storm is a wall of dust and sand lifted by strong convective winds, often ahead of a thunderstorm, cutting visibility to near zero within minutes. The ingredients are geographic: the Thar Desert and arid tracts supply loose dust, intense surface heating builds powerful updrafts, and the advancing monsoon trough provides the trigger. Climate and land-use change, including degraded commons and construction dust, are widely seen as intensifying the dust load these storms carry.

The damage is threefold. For health, fine dust spikes particulate pollution, triggering asthma, respiratory distress and eye injuries, with the elderly and outdoor workers worst hit. For agriculture, high winds lodge standing crops, strip flowers and young fruit, and sand-blast vegetation, while dust deposits on leaves cut photosynthesis. For infrastructure and transport, near-zero visibility disrupts road traffic and aviation, uproots trees and power lines, and damages kutcha structures. Management leans on nowcasting: IMD's dust-storm warnings, public advisories to stay indoors, and longer-term dust suppression through green belts, stabilisation of construction sites and restoration of degraded lands.

Avalanches and high-altitude operations: Siachen and SASE

An avalanche is the rapid downslope movement of snow, ice and debris, triggered when the snowpack's weight exceeds its bond to the slope, by fresh snowfall, warming, wind loading or human disturbance. In the Himalaya and Karakoram, avalanches are both a civilian hazard for mountain communities and soldiers' routes, and a military reality: the Siachen Glacier, where Indian troops hold some of the world's highest battlegrounds, loses more soldiers to avalanches, blizzards and extreme cold than to enemy action in most years, making avalanche forecasting a matter of force preservation.

The forecasting institution is SASE, the Snow and Avalanche Study Establishment, a DRDO laboratory that studies snowpack, issues avalanche warnings for the western Himalaya, and advises the armed forces on safe movement, route selection and the timing of operations. Its network of observatories monitors snow depth, temperature gradients and weak layers in the snowpack, the variables that decide whether a slope will hold or release. For disaster management, SASE is the counterpart of IMD for the cryosphere: a specialised forecasting agency whose warnings protect both soldiers and mountain civilians, and a reminder that India's hazard map extends from tropical cyclones to Himalayan snowfields.

Case study: Cyclone Phailin (2013), the evacuation benchmark

Cyclone Phailin struck Odisha in 2013 as a very severe cyclonic storm, and it remains India's benchmark for what early warning plus evacuation can achieve. Acting on IMD forecasts, Odisha evacuated about 1.2 million people within 36 hours, among the largest evacuations in India's history, into over 18,000 shelters stocked with emergency supplies. The death toll was limited to 44 despite the storm's intensity, earning international recognition as a model response and setting the standard that Cyclone Fani (2019) later matched with GIS, drones and pre-positioned NDRF teams.

How a tropical cyclone is classified

Declaring a drought: the norm behind the headline

A drought is declared; it does not simply happen. The India Meteorological Department treats an area as drought-affected when its rainfall deficiency reaches 26% or more of the long-term normal. About 68% of India is considered drought-prone, with roughly 33% chronically drought-prone and another 35% drought-prone. State governments make the formal declaration using indicators that combine rainfall deviation, dry spells, soil moisture and crop condition, which is why a meteorological drought on paper and a declared drought on the ground can arrive weeks apart.

UPSC and this topic: PYQ weightage

Atmospheric disasters appear in the mains mainly through drought and through current-affairs-anchored questions on cyclones and heatwaves. The actual PYQ on record:

• 2014 (12.5 marks)
• Current-affairs weightage

Key Terms

• National Cyclone Risk Mitigation Project (NCRMP): The National Cyclone Risk Mitigation Project is the World Bank-assisted programme, launched in 2011, to reduce cyclone vulnerability in coastal states through early warning systems, shelters, underground cabling and coastal bio-shields. Example: multipurpose cyclone shelters across Odisha and Andhra Pradesh were built under NCRMP
• Mukhya Mantri Jal Swavalamban Abhiyan: The Mukhya Mantri Jal Swavalamban Abhiyan is Rajasthan's state programme for village water self-sufficiency through johads, check dams and recharge structures in the arid state. Example: the Abhiyan revived traditional water harvesting to fight desert drought
• Cyclonic Storm (named by IMD): A cyclonic storm is the IMD stage at which a tropical system is named, with wind speeds of 62-88 km/h. Naming aids public communication of warnings. Example: Cyclone Remal (2024) was named when it reached the cyclonic storm stage
• mangroves and coastal bio-shields: Mangroves and coastal bio-shields are belts of salt-tolerant vegetation planted along coasts to weaken storm surges, trap sediment and protect settlements. They are living, self-repairing defences. Example: the mangroves of Bhitarkanika shielded inland Odisha during successive cyclones
• Extremely Severe Cyclonic Storm: An extremely severe cyclonic storm is the IMD category with wind speeds of 167-221 km/h, causing large-scale devastation. Example: Cyclone Amphan (2020) made landfall as an extremely severe cyclonic storm in West Bengal
• Very Severe Cyclonic Storm: A very severe cyclonic storm is the IMD category with wind speeds of 118-166 km/h, causing extensive damage to infrastructure. Example: Cyclone Yaas (2021) struck Odisha as a very severe cyclonic storm
• Heat Action Plan (HAP): A Heat Action Plan is a city's early-warning and response plan for extreme heat: temperature forecasts, public advisories, cooling centres, adjusted work hours and health-system readiness. Example: over 20 Indian cities now have HAPs modelled on Ahmedabad's pioneering plan
• Ahmedabad HAP of 2013: The Ahmedabad Heat Action Plan of 2013 was South Asia's first city heat plan, created after the deadly 2010 heatwave. Its early warnings, cool roofs and public outreach cut heat deaths sharply and became the national template. Example: NDMA's national heat guidelines drew directly on Ahmedabad's 2013 plan

• Siachen Glacier operations: Siachen Glacier hosts some of the world's highest military deployments, where avalanches, blizzards and extreme cold cause more casualties than combat in most years. Avalanche forecasting and cold-weather preparedness are therefore force-preservation measures. Example: The Siachen deployment is the standard case for why disaster forecasting matters to national security.

• Drought Monitoring Cells: Drought Monitoring Cells are state-level units that track rainfall, reservoir, crop and groundwater indicators to declare drought and trigger relief. Example: Karnataka's Drought Monitoring Cell issues weekly bulletins during the monsoon
• Odisha's cyclone model: Odisha's cyclone model is the state's end-to-end system for cyclone management: accurate IMD forecasts, mass evacuation to cyclone shelters, community volunteers and rapid restoration, built after the 1999 super cyclone. It is cited globally as best practice. Example: the evacuation of over a million people before Cyclone Fani (2019) with minimal casualties is the model's signature success
• Cyclone Amphan (2020): Cyclone Amphan (2020) was the super cyclonic storm that devastated West Bengal and Odisha in May 2020, with winds up to 185 km/h at landfall near Bakkhali. It caused about $14 billion in damage, among the costliest Indian Ocean cyclones. Example: Amphan's storm surge flooded the Sundarbans while Kolkata faced unprecedented urban damage

Practice questions