Mean summer temp in state rose 1.2°C in 70 yrs: Study

Hindustan Times

8 hours ago

Mumbai: A long-term assessment on heat trends and vulnerabilities in Maharashtra shows that despite advances in the arrival of the monsoon in recent years, instances of extreme heat are on the rise. Maximum temperatures during summers as well as prolonged stretches with temperatures above 40° Celsius have risen substantially over the past seven decades, the assessment shows. This signals a shift from episodic to chronic heat exposure, with profound public health consequences for vulnerable groups including infants, elderly people, those with chronic illnesses, and millions of informal sector workers, said experts.
As per the report compiled by the India Meteorological Department (IMD) and public health experts using 72 years of data (1951–2022), the mean summer maximum temperature in the state has risen by over 1.2°C – from 36.3°C in 1951 to 37.5°C in 2022. The number of days with temperatures exceeding 45°C have also spiked, especially in May – the state's hottest month. While such temperatures were virtually absent between 1951 and 1970, the trend escalated dramatically in the 1980s, and peaked in 2010 and 2015, when the number of extreme heat days were 65. The spike was especially pronounced in the Vidarbha region, in districts like Wardha and Yavatmal, marking them as persistent high-heat hotspots.
'We compiled this dataset from IMD and conducted a detailed region-wise analysis to understand the steady rise in temperatures and localised impacts,' said a senior official from the Maharashtra Disaster Management Department who was involved in the assessment. 'This dataset will now form the foundation for targeted climate-health policies. Since temperature patterns evolve over decades, this data will remain valid for years.'
Soaring mercury
According to the assessment, the mean maximum temperature in the state for May has increased from 40.17°C in 1951 to 41.19°C in 2019. Prolonged heat spells, defined by temperatures exceeding 40°C for more than two days, have also increased sharply during this period – while there were only 223 such instances in 1951, by 2022, the number had more than doubled to 451, with districts like Buldhana, Jalgaon, Hingoli, and Washim among the worst affected.
Such long exposures to heat lead to electrolyte imbalances, acute kidney injury, cardiovascular events, and even heat stroke-related delirium, said experts.
'A one-degree rise in average temperature may mean an actual micro-level temperature increase of 5-6°C,' said Ronita Bardhan, professor of sustainable built environment at the University of Cambridge. 'In densely populated cities like Mumbai, indoor temperatures may soar even higher, especially in slum tenements made of metal sheets, turning homes into death traps.'
Rise in the mercury raises skin temperatures and increases vulnerability, particularly for women who spend significantly more time indoors, said Bardhan. 'Biological and social factors compound risks,' she said. 'For instance, women sweat less than men and often avoid drinking water to limit bathroom visits due to lack of access, which accelerates dehydration.'
Ilan Kelman, professor of disasters and health at University College, London, echoed Bardhan on gendered disparity with regards to impact of heat.
'In India, it is often socially acceptable for men to urinate in public. But women can't,' said Kelman. 'So women working away from home tend to drink less to avoid using the toilet. That puts them at higher risk of dehydration and heatstroke.'
The combination of high heat and humidity was particularly dangerous, said Kelman.
'Fans blowing hot, humid air can actually accelerate dehydration, especially when nights remain hot and people don't cool down,' he said. 'Cognitive impairment is often the first sign – people stop recognising they need to rest, hydrate, or find shade. Without intervention, it progresses to multi-organ failure and death.'
Urban centres with increasing asphalt sprawl, reflective rooftops and declining tree cover comprise a separate but equally urgent crisis, said experts.
'For many poor communities, artificial cooling isn't even an option,' Kelman said. 'Informal settlements lack the infrastructure to support air conditioning. Even indoor garment workers are vulnerable in poorly ventilated buildings that heat up rapidly and offer no relief.'
Climatic shift
Dr Dileep Mavalankar, former director of the Indian Institute of Public Health in Gandhinagar and a key architect of India's first heat action plan for Ahmedabad, said India was no longer dealing with seasonal extremes but confronting a fundamental climatic shift.
'There's no denying the intensity of Indian summers,' he said. 'Yet today's heatwaves are not seasonal fluctuations—they are the clearest signals of a changing climate. Heatwaves are arriving earlier, lasting longer, and pushing beyond previously recorded limits.'
Many heat-related deaths, especially those related to cardiovascular collapse or worsening of chronic respiratory conditions, don't show up in official records, said Dr Mavalankar.
'Heat doesn't only kill through heatstroke,' he noted. 'It first impairs cognition and by the time people seek care, it's often too late.'
The under-reporting of heat-related ailments and deaths is a major barrier in both preparedness and accountability, he noted.
Anticipatory intervention
'Currently, we're in a reactive mode, but there's an opportunity in this urgency,' Bardhan said. 'We must integrate thermal resilience into housing schemes like 'Housing for All'. These can become invisible infrastructure, especially for women who are disproportionately exposed to indoor heat.'
Though Maharashtra has introduced a state-level heat action plan, execution remains patchy and key interventions – such as public hydration booths, early warnings, shaded workspaces, and awareness campaigns – often fail to reach remote villages and urban slums. Rural health centres also often report shortages of oral rehydration salts (ORS) and cool intravenous fluids during peak summer.
'Maharashtra must urgently shift from crisis response to anticipatory governance,' said Dr Malvankar. He cited the example of implementing the heat action plan in Ahmedabad, which showed that timely early warnings, public awareness, and access to hydration could save lives. 'Unless we scale these interventions to both rural and urban districts, we will continue to grossly underestimate the toll,' he warned.