Climate-driven heat exposed 117 million people in India to a month or more of risky heat between June and August 2026, according to a Climate Central analysis.

Between June and August this year, 117 million people in India spent a month or more under heat that would have been far less likely without a warming planet. That single number, from a new global analysis by Climate Central, puts India at the top of the world’s list for population exposed to climate-driven risky heat — ahead of China’s 94 million and Indonesia’s 83 million.

The finding sits inside a larger, starker pattern. Worldwide, over 1.5 billion people experienced 30 or more days of risky heat that climate change made significantly more likely this summer. On any single day of the season, more than a quarter of humanity felt a strong climate change signal in the local temperature. Climate Central’s scientists tracked this using their Climate Shift Index (CSI), which measures how much more likely a given day’s warmth was because of climate change, and flagged “risky heat days” as those hotter than 90% of what a place recorded between 1991 and 2020 — the threshold at which heat starts to strain the body.

The Global Climate-Driven Heat Scoreboard

Europe came out the most unusually hot continent on the planet this year, even though it was not the most populous one affected. Eighty-nine per cent of Europeans — nearly nine in ten — spent a month or more under risky heat. France and the Holy See tied for the largest temperature anomaly of any country, running 3.5°C above their historical norm, and seven of the world’s ten most abnormally hot countries were European. Fifty-four countries recorded their hottest June-to-August since 1970, France, Italy and the United Kingdom among them.

Asia, by contrast, carried the largest raw number of people through this heat: 2.8 billion, or 58% of the continent’s population, spent 30 days or more under conditions strongly shaped by climate change. India and Egypt were the two countries where more than 100 million people each crossed that threshold.

Africa’s story shows up less in totals and more in persistence. Six African countries spent at least 95% of the entire three-month period under a strong climate change influence — Rwanda for 91 days, Uganda for 89, Ethiopia for 88. For those populations, the season did not have an unusually hot patch; nearly the whole summer was one.

In North America, four in five people in the United States lived through a month’s worth of risky summer heat, with the average American gaining 23 such days from climate change and the average Canadian gaining 17.

India’s numbers, city by city

Nationally, India ran 0.7°C warmer than its 1991–2020 June-to-August average, and the average Indian experienced climate change’s fingerprint on local temperature for 39 days across the three months — better than a third of the entire season.

City-level data obtained alongside the release shows how unevenly that heat landed.

Source: Climate Central, June–August 2026 city dataset.

Two different stories run through these columns, and conflating them misses the point.

Mumbai tops the country for sheer duration: 86 of the 92 days in the season carried a strong climate change signal, more than any other Indian city measured. But of Mumbai’s 24 risky heat days, only four were added by climate change — the city runs hot most of the year regardless, so the climate contribution to its worst days is comparatively small. Pune and Nashik, sitting in Mumbai’s own state, show almost the opposite ratio: nearly every risky heat day they had this summer would not have happened without climate change.

Chennai had both the most risky heat days in the country — 40 — and the most added by climate change — 30. That combination makes it the city where the analysis draws the clearest straight line between a hot summer and a warming climate. Tiruchirappalli and Madurai, both in Tamil Nadu, follow the same pattern: every risky heat day counted in each city was one climate change made more likely.

Srinagar is the outlier worth pausing on. A city known for temperate summers recorded 53 risky heat days, more than any other Indian city in the dataset, of which 29 were attributed to climate change — a scale of departure from its own historical baseline far larger than what Mumbai or Delhi saw from theirs.

Where the heat did not arrive

Not every Indian city ran hotter than usual. Jaipur’s seasonal average came in 0.4°C below its 1991–2020 norm, Kota 0.2°C below, and Bhopal 0.1°C below — small numbers, but real ones, in a summer when most of the country and the world trended the other way. Even so, none of the three escaped the climate signal entirely: Jaipur still logged three risky heat days attributable to climate change, Kota three, Bhopal one. The exceptions are a reminder that a warming climate does not raise every thermometer in lockstep, even as it raises the odds almost everywhere.

What the numbers are measuring

The CSI framework Climate Central uses does not ask whether a heatwave happened — it asks how much more likely climate change made it. A CSI level of 2 or higher, the threshold used throughout this analysis, means the day’s warmth was at least twice as likely because of the human-driven build-up of greenhouse gases. That is a probability statement about cause, not a one-off weather reading, which is what allows the same framework to compare Mumbai’s long hot stretch against Chennai’s sharper, more clearly climate-driven spike.

Kristina Dahl, Climate Central’s vice president for science, described the pattern as one where “human-driven warming is pushing communities beyond safe physical limits” — a line written with Europe and North America in mind as much as South Asia. The India numbers suggest the same pressure is arriving unevenly within a single country: some cities absorbing a long, low-grade climate signal across most of the summer, others taking a shorter but far sharper hit concentrated into their worst weeks.

August 2026 tied July 2023 as the warmest month ever recorded globally. But the significance of the latest record lies beyond the temperature figure itself. Heat was building across the oceans, western Europe endured its hottest summer on record, and in India, a strengthening El Niño was adding pressure to an already uneven monsoon.

The global average surface air temperature in August was 16.96°C, 0.85°C above the 1991–2020 average, making it the warmest August in the ERA5 record. Relative to the estimated 1850–1900 pre-industrial average, temperatures were 1.65°C higher. It was the first month to cross 1.5°C since November 2025.

A single month above 1.5°C does not mean the Paris Agreement’s long-term temperature threshold has been breached. That threshold is assessed over a much longer period. What the August figure does show is how far short-term temperatures can now move beyond the historical baseline.

The Oceans Are Sending Their Own Signal

The heat was not confined to the atmosphere. Extra-polar oceans recorded their warmest August in the ERA5 dataset, with an average sea surface temperature of 21.07°C. That was also tied with March 2024 for the highest monthly average recorded for any month.

The tropical Pacific was particularly warm as El Niño conditions strengthened. Around Europe, Atlantic and western Mediterranean waters reached record August temperatures, alongside widespread strong or severe marine heatwaves.
The ocean matters here because its warmth can influence atmospheric circulation, rainfall and marine ecosystems. In 2026, its connection to India’s monsoon was particularly relevant.

India Was Watching the Pacific

For India, the global temperature record arrived against a difficult monsoon backdrop. The India Meteorological Department had forecast below-normal rainfall for the 2026 southwest monsoon. By August 2, cumulative rainfall was 12% below the long-period average, with 47% of districts facing deficient or large-deficient rainfall. IMD attributed part of the suppressed monsoon circulation to the development and strengthening of El Niño conditions in the equatorial Pacific.

The deficits were not uniform. By early August, Kerala and Mahe were 22% below normal, while 16 meteorological subdivisions had rainfall deficits ranging from 20% to 38%.

That does not mean August’s global heat record caused India’s rainfall deficit. The monsoon is shaped by several interacting climate systems, and El Niño is only one of them. But the concurrence is significant: while the tropical Pacific was registering exceptional warmth, India was dealing with a monsoon season that was already running below its seasonal benchmark.

Europe Shows the Cost of Persistent Heat

Western Europe had its warmest summer on record in 2026, surpassing the previous record set in 2003. Heatwaves arrived early and persisted through the season. Heat was accompanied by prolonged dryness. Severe drought conditions were reported in France, the UK, Hungary, Romania and Serbia, while exceptionally low river flows affected the Rhine, Danube, Southern Bug and Dnieper.

The connection is important: extreme heat does not operate in isolation. When high temperatures persist alongside rainfall deficits, their effects can accumulate across agriculture, water systems, ecosystems and wildfire risk.

The Record Is Becoming the Background

August’s warmth is more revealing when viewed alongside the other records surrounding it. The month saw exceptional ocean temperatures and low sea-ice levels, while June–August was jointly the warmest global summer on record, matching 2024.

The challenge in interpreting such records is to look beyond the headline number. A record month does not mean every region experienced record heat. It means the global climate system is operating from a warmer baseline, while regional weather continues to be shaped by monsoons, El Niño, ocean temperatures and other climate patterns. August 2026 was another record. Its importance may ultimately lie in how quickly records such as this stop looking extraordinary.

A city can draw up a climate adaptation plan quickly. Changing what people experience on its streets takes years. Across Europe, local governments are investing in measures meant to make urban areas more resilient to rising temperatures, flooding and other climate risks. The 2026 Europe Cities Report by the Lancet Countdown recorded 1,519 planned or implemented adaptation actions across more than 850 cities. These include green infrastructure, flood defences, ecological restoration and community engagement.

There are signs that some of these interventions are making a difference. Summer surface urban heat-island intensity declined in 88% of the cities analysed, with an average reduction of 0.7°C. But progress is uneven. Nearly one-third of the cities reported financial and technical constraints as major barriers to adaptation. For residents, the value of these measures is ultimately measured at a much smaller scale: a shaded road, a cooler neighbourhood, a bus stop protected from direct sun or a safer route to work and school.

Climate Adaptation: Where the Trees are Matters

Trees are one of the most visible ways cities can respond to heat, but the amount of urban tree cover varies widely across Europe. Swedish cities had average tree cover equivalent to 41.6% of urban land in 2020. Eleven of the 14 cities studied had at least 30% tree cover. Bulgaria’s average was 22%, while Spain recorded 13.2%, France 9.2% and Ireland 3.4%. The figures do not establish a direct link between tree cover and a city’s overall heat risk. They do, however, show how different the urban environments are in which people are exposed to a warming climate.

Dr Rita Issa, a family medicine and climate-health consultant at WHO, identifies green spaces as an intervention that can support physical and mental health while helping cities respond to environmental pressures. She also points to low-emission zones as an example of a policy that can produce health benefits alongside environmental gains.

But where greenery is placed matters. A park at the edge of a neighbourhood may offer little protection to someone walking along a treeless road or waiting at an exposed bus stop. Trees lining routes used by children, older people and pedestrians can affect heat exposure much more directly.

Adaptation Measured by its Impact

The 1,519 adaptation actions in the report cover a broad range of interventions. Community engagement accounted for 8.1% of the actions, green infrastructure for 6.4%, flood defence for 5.1% and ecological restoration for 4.5%.

Of these actions, 596, or 39.2%, reported public-health co-benefits. That provides a useful way of looking at urban adaptation. Infrastructure is only part of the story. What matters is whether an intervention reduces exposure or produces measurable benefits for residents. Francesca de’Donato of ASL Roma 1 says city-level indicators can help connect scientific evidence with local policy while allowing health co-benefits to be measured and monitored.

That approach shifts the focus from the number of projects completed to what they achieve. A city can count the trees it has planted or the flood barriers it has built. It is more useful to know whether those measures have reduced heat exposure, improved air quality or made vulnerable neighbourhoods safer.

Heat Changes Cities’ Movement

Transport is closely tied to this question. The cities studied in Sweden and Spain recorded an average sustainable transport score of 5.3 out of 10. Ireland scored 5.2, France 5 and Bulgaria 4.6. Access to public transport also differed. Only 23% of urban areas in the Swedish cities studied were within 250 metres of a public transport stop. The corresponding figures were 32% in Spain, 31% in Ireland and 30% in France.

Then there is the question of shade. Trees covered 27.7% of cycling and shared cycling-pedestrian paths in the Swedish cities studied. The proportion fell to 9.4% in Spain and 8.3% in Ireland.

These indicators are presented as measures of transport infrastructure, but they also say something about exposure to heat. A journey that is manageable in moderate weather can become difficult when temperatures rise and the route offers little shade. Jordi Jové of the Barcelona Metropolitan Area links sustainable mobility with lower emissions, cleaner air and healthier urban environments. For cities facing more frequent heat, how people move around the urban environment becomes part of the climate-health equation.

The Cost of Adaptation Remains a Constraint

The biggest obstacle may not be a lack of possible solutions. Nearly one-third of the cities in the report identified financial and technical constraints as major barriers to adaptation. Many measures also require continued investment after they are built. Trees need space and maintenance. Public transport systems require long-term funding. Heat-health measures depend on cooperation between municipal authorities, health services and communities. The 596 adaptation actions reporting public-health co-benefits point to one way of making these investments work harder. A single intervention can address several problems.

A greener street can provide shade and improve the surrounding environment. Better public transport can reduce emissions and traffic-related pollution. Streets designed for walking can make everyday journeys easier while reducing dependence on cars. The difficulty is ensuring that these benefits do not remain concentrated in parts of a city that already have better infrastructure.

The Real Measure of a Climate-ready City

The report presents a European urban landscape that is changing, but not at the same pace everywhere. Some cities have reduced their summer heat-island intensity. Others have extensive tree cover or are investing in transport, flood protection and ecological restoration. Yet many still face financial and technical limits. Lorna Benton of Pathfinder says city-level assessments can help cities understand the health risks they face and identify opportunities to build healthier, more resilient and lower-carbon urban environments.

The next step is whether that information changes decisions on the ground. For residents, adaptation is not experienced as a number in a municipal report. It is the shade on a walk to school, the temperature at a bus stop, the availability of a nearby green space or the ease of reaching a clinic without spending too long in the heat.

That is where the success of urban climate policy becomes tangible. European cities have started changing their streets, public spaces and transport systems. The larger challenge is to make those changes reach the neighbourhoods and people most exposed to a hotter climate.