Expert Explains | What makes this summer particularly intense for India, and how better data collection can help

Temperatures in and around India on the afternoon of May 19, 2026. Shades of yellow show temperature between 20 to 30 degrees Celsius, orange between 30 and 40 degrees, and deep reds beyond 40 degrees. (Windy.com screengrab)

The current heat pattern over northwest India, central India and parts of Pakistan is partly a regular seasonal phenomenon and partly an intensified heat wave situation. During April and May, these regions naturally experience extreme heating due to high solar radiation, dry continental winds, low soil moisture and the formation of seasonal low-pressure heat zones over Rajasthan and adjoining Pakistan. Therefore, the presence of red and orange shades during the pre-monsoon season is climatologically normal.

However, what is concerning this year is the intensity, persistence and large spatial extent of the heat. Temperatures are remaining abnormally high over prolonged periods with limited nighttime cooling, indicating severe heat wave conditions. Reduced pre-monsoon rainfall, persistent dry air circulation, extensive land surface warming and Urban Heat Island effects (the latter a result of unplanned urbanisation and construction) are further amplifying the situation.

Climate change is also acting as a background stress multiplier. While heat waves are not new to India, rising baseline temperatures are increasing their frequency, duration and severity, making extreme summer conditions more common across the region.

How are heat and temperature maps generated, and how should they be read?

All maps showing temperature values are not computed using the same method.

First, some are simple interpolations of air temperature data measured by weather stations observed at certain points, scaled to cover the entire area of interest. The finer the observation network, the better the accuracy. These stations come from government agencies, private networks, and individual climate enthusiasts.

Second, remote sensing captures temperature over larger areas through thermal sensors aboard satellites. These measure surface skin temperature, specifically the energy radiated from the ground, which is then translated into surface temperature estimates through physical relationships between emitted radiation and temperature.

Kartavya path in New Delhi. (Express photo by Haobijam Chinglemba Meitei)

This became a widely used tool for studying thermal variations since the early 1980s, with global daily coverage expanding significantly after 2000, thanks to sensors like the Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat thermal sensors.

Third, air temperature values are calculated using numerical weather model simulations. These ingest data from ground stations, satellite-derived land surface temperatures, humidity, solar radiation, cloud cover, rainfall patterns, soil moisture, land use, sea surface temperature, and topography.

The key advantage is predictive capability, between four and 15 days, depending on the model. Platforms like Windy.com use the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Global Forecast System (GFS), the most popular models.

ECMWF’s Integrated Forecasting System runs deterministic forecasts up to 15 days. IMD operates its own Numerical Weather Prediction (NWP) suite based on an India-adapted GFS and ingests ECMWF data for heat wave guidance and extended-range forecasts.

So, whenever you see a map showing intense temperatures, first ask — is it showing air or surface temperature? Then question the source. Each method tells its own story, and some carry the imprint of local surface and microclimatic conditions that a global model simply cannot capture accurately.

What is driving India’s rising heat — global climate patterns or local factors?

The answer is both.

On the global side, two factors stand out. First, El Niño conditions are developing in the equatorial Pacific, with onset projected between May and July. It is a climate phenomenon marked by changes in sea temperatures along the eastern Pacific Ocean, coupled with fluctuations in the overlying atmosphere.

Even at this early stage, there are indications of suppressed moisture over the subcontinent and intensifying pre-monsoon heat build-up. The IMD has already projected the 2026 southwest monsoon at 92% of the long-period average (below normal), with El Niño as a primary driver.

Second, long-term anthropogenic warming is steadily raising baseline temperatures. Heat wave frequency in India has been on a consistent upward trend since 1961, with projections indicating a further rise of 12 to 18 days under continued warming trajectories.

Local factors determine how that heat is felt. Weak western disturbances, prolonged dry spells, and reduced cloud cover intensify conditions significantly. In urban areas, the Urban Heat Island effect, driven by dense infrastructure, vehicles, air-conditioning, and industries, makes cities measurably hotter. In rural areas, forest fires, biomass burning, and barren exposed landscapes amplify surface heating.

The heat we experience is never due to a single factor, and ground-based observations often remain the most reliable measure of local heat stress.

How is extreme heat affecting people, livelihoods and ecosystems?

Extending well beyond direct temperature readings, heat directly affects humans, animals, and ecosystems, though human consequences are often the most visible.

Raj Laxmi the elephant enjoys a shower to beat the heat, at the Delhi Zoo in April 2026. (Express photo by Praveen Khanna)

The most immediate impact is the decline in productivity among outdoor workers. Daily wage workers, construction labourers, street vendors, and gig workers cannot avoid heat exposure because their livelihoods depend on continuous physical presence. Economic compulsions override precautionary advisories, making this a social vulnerability as much as a climatic one.

Heat stress also disproportionately affects those in informal settlements where access to cooling, ventilation, green cover, and a reliable water supply is limited. Among vulnerable populations, the elderly and infants face heightened risk as their bodies regulate temperature less efficiently.

Heat also aggravates comorbidities like cardiovascular disease, respiratory illness, and diabetes, and in severe cases leads to dehydration, heat exhaustion, heat stroke, and death. Heat-related mortality, however, remains significantly underreported due to the complexity of direct attribution.

Ecologically, rising temperatures dry out vegetation, reduce water availability, and stress wildlife and livestock. Prolonged heat and drought conditions create fire-prone landscapes, making forest fires more frequent and intense, which in turn release carbon, destroy canopy cover, and further amplify local surface temperatures.

Heat is, therefore, no longer a matter of seasonal discomfort alone. It is actively shaping public health, work efficiency, urban living conditions, and ecological stability for millions.

How can data and geospatial technologies improve heat mitigation strategies?

Without accurate and spatially detailed observations, heat mitigation strategies often remain generic and less effective on the ground.

One of the key roles of data is to distinguish between global climatic drivers and local heat sources, helping us understand how climate change interacts with urbanisation, land-use changes and local environmental conditions. Geospatial datasets today help map the prevalence of factors like Urban Heat Islands and vegetation loss, enabling targeted interventions rather than one-size-fits-all responses.

Heat behaviour is highly location-specific. A strategy that works in one city may not work elsewhere because local climate, population density and anthropogenic heat emissions vary significantly. This is why India requires denser weather station networks and improved thermal-monitoring systems.

There is also an urgent need for dedicated thermal payloads and high-resolution thermal remote sensing systems to continuously monitor land surface temperatures, identify heat hotspots, study forest fires and understand localised thermal behaviour.

More research and development are required to identify mitigation strategies that work for specific local conditions. Parallel efforts are equally necessary to minimise anthropogenic heat sources through better environmental management, urban planning and energy-use practices.

Heat mitigation, therefore, requires a balanced approach in which both the impacts and the sources of heat are addressed simultaneously through scientifically-informed policy interventions and geospatially-driven planning.