Large parts of Pune’s most built-up neighbourhoods endured dangerous levels of heat exposure on nearly half of the hottest summer days last year, according to a field-based scientific assessment that tracked real-world thermal stress across the city. The findings sharpen concerns about urban design, worker safety and climate preparedness in one of India’s fastest-growing metropolitan regions.
The assessment, conducted during April and May 2024, used the Wet Bulb Globe Temperature (WBGT) index a measure that factors in air temperature, humidity, solar radiation and wind speed to estimate how heat is experienced by the human body. Unlike conventional temperature readings, WBGT reflects actual physiological stress, making it more relevant for outdoor workers, commuters and vulnerable populations. Researchers installed sensors at approximately human height and recorded readings at five-minute intervals through the day. Three distinct urban settings were monitored: a dense inner-city academic precinct, a moderately built campus environment and a greener institutional zone on the outskirts.
The data reveal a clear urban heat island pattern. The most urbanised site recorded extreme heat stress on roughly 44% of observed peak-summer days. The moderately developed campus followed at around 37%, while the greener peripheral campus saw extreme conditions on about one-third of monitored days. Even when only fully comparable days were analysed, the ranking remained consistent. Urban climate experts say the divergence underscores how built density, paved surfaces and limited tree cover amplify Urban Heat Stress. Concrete and asphalt absorb and re-radiate heat, while sparse vegetation restricts natural cooling through evapotranspiration. As Pune’s real estate footprint expands, these microclimate effects are becoming more pronounced.
Median daily peak WBGT levels also reflected incremental differences. The densest zone consistently registered slightly higher peak heat stress than the other two locations a small variation numerically, but significant in terms of health risk thresholds. Scientists involved in the study identified preliminary trigger values for Pune, indicating that WBGT readings beyond 31.5°C represent elevated risk, with progressively severe categories beyond 32°C and 33°C. Peak Urban Heat Stress occurred between early and mid-afternoon, typically between 1 pm and 3 pm. Wind direction and speed influenced exposure levels, with stronger airflow helping to dissipate heat load. Air temperature emerged as the dominant driver, while humidity showed an inverse daily pattern.
Urban planners note that such granular data could inform zoning decisions, heat action plans and building codes. Shading strategies, reflective roofing, permeable surfaces and increased tree cover are among measures that can moderate heat retention in dense precincts. The implications extend beyond public health to labour productivity, electricity demand and real estate viability. The researchers emphasised that the findings are based on a single season of field measurements and call for multi-year monitoring to assess longer-term trends. As climate projections indicate more frequent and intense heatwaves across western India, sustained tracking of Urban Heat Stress may become central to how cities plan growth and protect the people who power them.
Pune Dense Zones Face Heat Stress Surge
