Delhi’s ground is getting hotter, faster. A new satellite-based study tracking 11 years of data across all 247 municipal wards has found that the city’s land surface temperatures have climbed steadily, and that March 2026 marked a moment never recorded in the history of the data.
The study was conducted by Envirocatalyst, an environmental think-tank, which processed Landsat satellite imagery at a 30-metre resolution to map ward-level heat conditions across Delhi’s summers from 2015 to 2026. The findings show a city under mounting thermal pressure, with some neighbourhoods heating far faster than others.
Delhi’s mean land surface temperature in March rose from 29.1 degrees Celsius in 2015 to 32 degrees in March 2026, a rise of 2.8 degrees in just 11 years. Data from the India Meteorological Department’s Safdarjung station confirmed the same direction, showing the mean March maximum air temperature rose from 30.0 degrees in 2011 to 32.6 degrees in 2026.
What Is Land Surface Temperature?
Land surface temperature, or LST, is the heat emitted directly by the ground as measured from space. It is not the same as air temperature, the number shown on a standard weather forecast. LST measures how hot the actual surface of the earth is: roads, rooftops, concrete pavements, open soil, and water bodies.
When the sun heats a tarmac road or a concrete building, that surface absorbs and retains far more energy than a tree-covered patch of land or a lake. The result is a hotter ground and, in turn, hotter air above it. This is what drives the urban heat island effect, the well-documented phenomenon where cities are measurably hotter than surrounding rural areas.
The study uses the Universal Thermal Climate Index, or UTCI, to measure what heat actually feels like on the human body. UTCI brings together air temperature, radiant heat, humidity, and wind to calculate the physiological strain a person actually experiences. A reading above 26 degrees Celsius is classified as moderate heat stress. Above 32 degrees, it becomes strong heat stress.
In March 2015, not one of Delhi’s 247 wards crossed the 26-degree moderate heat stress threshold. That figure remained almost unchanged for the following decade. In March 2025, just one ward crossed it.
In March 2026, all 247 wards crossed it simultaneously. The analysis described it as “the first time in the 11-year satellite record that March has left no ward of Delhi at thermal rest.”
Where the Heat Hits Hardest
Within the same city, in the same month, under the same official weather alert, surface temperatures varied by five full degrees. In March 2026, Mahipalpur was the hottest ward at 34.4 degrees Celsius, followed by Harkesh Nagar at 34 degrees. The coolest ward, Nangal Thakran, recorded 29.2 degrees.
Over the full 11-year period, Sangam Vihar-A in south Delhi recorded the steepest March LST increase, 6.1 degrees. Meethapur, Sangam Vihar-B, Madangir, and Tigri each saw rises of between 4.9 and 5.2 degrees. At the other end, Prem Nagar and Isapur recorded the lowest increases at just 0.6 degrees each.
In April, Delhi’s mean LST rose by 3.5 degrees between 2015 and 2025. Bhati ward recorded the highest April increase at 6.1 degrees, followed by Madanpur Khadar East and Badarpur at 5.9 degrees each.
In May, surface temperatures in individual wards reached 52 degrees Celsius. Wards including Anand Vihar, Badarpur, Harkesh Nagar, Isapur, Jhilmil, Meethapur, Sarita Vihar, and Tughlaqabad all recorded these extreme readings. The city’s average LST in May across 2015 to 2025 stood at 44.1 degrees. The single hottest ward across that entire period was Isapur in the Najafgarh zone, where the average May LST reached 50.7 degrees.
In June, delayed monsoons pushed the city-wide mean close to or above 47 degrees Celsius, 47.6 degrees in 2019 and 46.9 degrees in 2024. Every single ward remained in the strong heat stress zone, with UTCI readings above 32 degrees, in every year from 2015 to 2025 without a single break.
Why Ground Keeps Getting Hotter
The answer lies in what has replaced Delhi’s green spaces. Concrete, asphalt, and brick absorb solar radiation and release it slowly as heat. Trees, water bodies, and open soil absorb water and release it through evaporation, a natural cooling mechanism. When those surfaces disappear, temperatures rise.
“Areas that once had parks, water bodies or small vegetation cover were replaced by constructed surfaces. That directly contributes to the rise in surface temperature,” said Sunil Dahiya, founder of Envirocatalyst.
Dense residential colonies have seen some of the steepest climbs. Experts noted that rapid urban growth with little green cover has created concentrated pockets of heat stress that standard city-level data completely misses.
Experts are calling for ward-specific heat action plans rather than broad city-wide responses that obscure the severity in the worst-affected areas. Cooling shelters, natural construction materials, and the greening of urban corridors have been identified as immediate priorities.
“The important point of this analysis is that it shows which locations in Delhi need localised heat adaptation plans and granular policy changes,” Dahiya said.
He added that the threat could no longer be treated as secondary. “While we discuss other urban challenges, we cannot afford to miss the compounding threat of heat stress. This ward-level data can be used by the government and policymakers to make real-time, localised decisions,” he said.
The data is clear and the ward-level map is ready. What remains is the political will to act on it before the next summer makes March 2026 look mild.
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