During the peak summer months of April and May 2024, the research team carried out readings every hour, every day between 9 am and 6 pm. (File Photo)All through April and May this year, as the maximum and minimum temperatures soared in Pune, a team of scientists and students from the India Meteorological Department (IMD), Fergusson College, and the Indian Institute of Science Education and Research (IISER), were performing detailed measurements to quantify the ambient heat in a manner that is directly relevant to humans.Their data went beyond the air temperature. It was the wet-bulb globe temperature (WBGT) that the team focused on.According to the IMD, WBGT is one of the most commonly used indices by many organisations since the 1960s. “This index was originally invented in the 1950s in efforts to lower the risk of heat disorders during the training of the US Army and Marine troops. Since that time, WBGT has been applied in other settings, and is widely used for the evaluation of occupational heat stress exposure,” says IMD.A high temperature almost definitely means it’s dangerous, but dangerous to whom and to what extent – this was what the study sought to measure. “The maximum temperature is useful as an indicator, but it is not particularly useful as a decision making number or a quantity. The reason WBGT is used is it has published thresholds for danger levels,” says Dr Joy Merwin Monteiro, Assistant Professor, Department of Earth and Climate Science, IISER Pune.India is one of countries outside the global north that have not calibrated WBGT to their population. In the US, a WBGT of less than 26.7 degree Celsius (approx) means that new athletes can undertake unlimited activity with primary cautions or extreme exertion but must schedule mandatory rest or water breaks. On the other end of the spectrum, an intense WBGT reading of more than 32.2 degree Celsius (approx) indicates that all athletes must suspend practice or have mandatory breaks as directed by the sports administration.In February this year, the collaborative team across IMD, FC and IISER, led by Rajib Chattopadhyay, published the first-ever study on WBGT in the city, “Quantifying heat stress using wet bulb globe temperature measurements during summer 2024 from field experiments in Pune”.For the study, three locations were chosen to install WBGT meters –IISER, Fergusson College (FC), and Agriculture College. During the peak summer months of April and May 2024, the research team carried out readings every hour, every day between 9 am and 6 pm. “It was found that maximum heat stress usually occurred between 1 pm and 3 pm, with variations depending on the location,” says the study.The findingsStory continues below this adThe findings from the study established the WBGT threshold limits for Pune. These were 31.5 degree Celsius, 32 degree Celsius and 33 degree Celsius. “This corresponds to low, moderate, and extreme heat stress levels,” says the study. While the researchers found that a strong positive correlation between WBGT and ambient temperature, relative humidity and wind speed had a reverse correlation. “Notably, southerly winds contributed most significantly to heat stress,” says the study.According to Monteiro, the findings equip policymakers, urban planners and environmentalists with essential insights. The data can be used as foundations to decide strategies to mitigate the challenges of climate change and enhance urban resilience against heat stress.Monteiro says that it is essential to understand heat stress in a more holistic manner, and using WBGT instead of just air temperatures is an important step in this direction. This holistic measurement is particularly important in the context of the health of the elderly and outdoor workers, among others. “If these measurements are carried out in a larger scale across different urban morphologies, it can also quantify how urban design and vegetation will influence heat stress level,” says Monteiro.Dipanita Nath is a Senior Assistant Editor at The Indian Express, based in Pune. She is a versatile journalist with a deep interest in the intersection of culture, sustainability, and urban life. Professional Background Experience: Before joining The Indian Express, she worked with other major news organizations including Hindustan Times, The Times of India, and Mint. Core Specializations: She is widely recognized for her coverage of the climate crisis, theatre and performing arts, heritage conservation, and the startup ecosystem (often through her "Pune Inc" series). Storytelling Focus: Her work often unearths "hidden stories" of Pune—focusing on historical institutes, local traditions, and the personal journeys of social innovators. Recent Notable Articles (December 2025) Her recent reporting highlights Pune’s cultural pulse and the environmental challenges facing the city during the winter season: 1. Climate & Environment "Pune shivers on coldest morning of the season; minimum temperature plunges to 6.9°C" (Dec 20, 2025): Reporting on the record-breaking cold wave in Pune and the IMD's forecast for the week. "How a heritage tree-mapping event at Ganeshkhind Garden highlights rising interest in Pune’s green legacy" (Dec 20, 2025): Covering a citizen-led initiative where Gen Z and millennials gathered to document and protect ancient trees at a Biodiversity Heritage Site. "Right to breathe: Landmark NGT order directs PMC to frame norms for pollution from construction sites" (Dec 8, 2025): Reporting on a significant legal victory for residents fighting dust and air pollution in urban neighborhoods like Baner. 2. "Hidden Stories" & Heritage "Inside Pune library that’s nourished minds of entrepreneurs for 17 years" (Dec 21, 2025): A feature on the Venture Center Library, detailing how a collection of 3,500 specialized books helps tech startups navigate the product life cycle. "Before he died, Ram Sutar gave Pune a lasting gift" (Dec 18, 2025): A tribute to the legendary sculptor Ram Sutar (creator of the Statue of Unity), focusing on his local works like the Chhatrapati Shivaji statue at Pune airport. "The Pune institute where MA Jinnah was once chief guest" (Dec 6, 2025): An archival exploration of the College of Agriculture, established in 1907, and its historical role in India's freedom struggle. 3. Arts, Theatre & "Pune Inc" "Satyajit Ray, Ritwik Ghatak were not rivals but close friends, says veteran filmmaker" (Dec 17, 2025): A deep-dive interview ahead of the Pune International Film Festival (PIFF) exploring the camaraderie between legends of Indian cinema. "Meet the Pune entrepreneur helping women build and scale businesses" (Dec 16, 2025): Part of her "Pune Inc" series, profiling Nikita Vora’s efforts to empower female-led startups. "How women drone pilots in rural Maharashtra are cultivating a green habit" (Dec 12, 2025): Exploring how technology is being used by women in agriculture to reduce chemical use and labor. Signature Style Dipanita Nath is known for intellectual curiosity and a narrative-driven approach. Whether she is writing about a 110-year-old eatery or the intricacies of the climate crisis, she focuses on the human element and the historical context. Her columns are often a blend of reportage and cultural commentary, making them a staple for readers interested in the "soul" of Pune. X (Twitter): @dipanitanath ... Read MoreClick here to join Express Pune WhatsApp channel and get a curated list of our storiesTags:IMDSummer heat