Explained: Why Is It So Hot In Delhi And What You Should Do To Stay Safe

Delhi is currently experiencing an intense heatwave, with temperatures forecasted to reach a staggering 46 degrees Celsius. The minimum temperature in the capital was recorded at 29.2 degrees Celsius, which is 2.6 degrees above the normal. Relative humidity was measured at 48 per cent at 8:30 am today. The India Meteorological Department (IMD) has predicted mainly clear skies with strong surface winds, compounding the severe heatwave conditions.

But why is it so hot in the national capital?

The extreme heat in Delhi is part of a broader heatwave affecting large parts of northern and central India. On Sunday, temperatures soared to an unprecedented 50 degrees Celsius in Rajasthan's Phalodi. This is the highest temperature recorded in India since June 2019, when Churu, another city in Rajasthan, hit 50.8 degrees Celsius.

Extreme Heat Across North India 

This heatwave is not just confined to the northern plains but has also impacted the hills of Himachal Pradesh, Assam, and Arunachal Pradesh. During the sixth phase of the ongoing general elections, voters in states such as Uttar Pradesh, Haryana, and Delhi faced extreme heat, with temperatures in the capital exceeding 45 degrees Celsius in several locations. Polling booths in many areas lacked adequate facilities like water, coolers, and chairs, leading to voters fainting due to the harsh conditions.

Several cities across India reported record-breaking temperatures recently. In West Bengal's Cooch Behar, the temperature reached 40.5 degrees Celsius, while Assam's Silchar hit 40 degrees, and Arunachal Pradesh's Itanagar recorded 40.5 degrees Celsius. These extreme temperatures have been widespread, with at least 17 locations in Punjab, Haryana, Rajasthan, Uttar Pradesh, Gujarat, and Madhya Pradesh recording temperatures of 45 degrees Celsius or higher.

Rajasthan has been particularly affected, with Barmer reaching 48.8 degrees Celsius, Jaisalmer 48 degrees, and Bikaner 47.2 degrees. The state's disaster management department has directed district collectors to provide necessary relief to people, animals, and birds. The extreme heat is expected to persist in Delhi, Rajasthan, Punjab, Haryana, Chandigarh, Uttar Pradesh, Madhya Pradesh, Gujarat, Chhattisgarh, and Maharashtra until the end of May, with severe conditions also affecting the hills of Himachal Pradesh, Assam, and Meghalaya.

Haryana and Punjab are also under severe heatwave conditions, with temperatures soaring above normal limits. In Haryana, Mahendragarh recorded 47 degrees Celsius, while Rohtak and Hisar reported 46.7 and 46 degrees, respectively. Similarly, Punjab's Amritsar reached 45.2 degrees, and Ludhiana 44.8 degrees. Chandigarh, the common capital of both states, saw temperatures of 44.5 degrees Celsius. The heatwave is expected to continue in these regions until May 29.

The IMD has issued a 'red' warning for several regions, including Rajasthan, Punjab, Haryana, Chandigarh, Delhi, west Uttar Pradesh, and Gujarat. This indicates a very high likelihood of heat illness and heatstroke across all age groups. The IMD also noted that warm night conditions will exacerbate heat stress in Uttar Pradesh, Punjab, Haryana, Delhi, and Rajasthan over the next four days. High night temperatures are especially dangerous as they prevent the body from cooling down, an issue exacerbated by the urban heat island effect, where cities remain significantly hotter than their rural surroundings.

Heat Multiplier Effect

Akash Vashishtha, founder-secretary of the Society for Protection of Environment and Biodiversity, in an interview with news agency PTI, explained that urban areas like Delhi-NCR become heat chambers due to land and surface concretisation, leading to a heat multiplier effect. The urban heat island effect traps heat in the lower atmosphere, significantly raising ambient temperatures. To mitigate this, Mr Vashishtha said there is a need to keep ground surfaces vegetated to absorb solar radiation and reduce heat reflection.

The intense heat in India is also straining power grids and depleting water bodies, triggering drought-like conditions in various regions. The Central Water Commission reported that water storage in 150 major reservoirs reached a five-year low last week, worsening water shortages and affecting hydropower generation. In Delhi, water levels in the Yamuna river have dropped, impacting water supply. The city's power demand hit a record 8,000 megawatts as air conditioners and coolers ran at full capacity.

The heatwave is placing a significant burden on low-income households, which often have limited access to water and cooling facilities. Poorly ventilated and inadequately sheltered informal housing exacerbates the impact of extreme heat on vulnerable populations. Outdoor workers, the elderly, and children are at higher risk of heat exhaustion and heatstroke.

Anna Walnycki of the London-based International Institute for Environment and Development said, "Low-income households have limited capacity to adapt to extreme heat because of poor access to water and electricity. Additionally, the design and construction of informal houses often mean there is poor ventilation and little shelter from extreme heat." 

The World Health Organisation reports that over 166,000 people died from heatwaves between 1998 and 2017, with India alone reporting 3,812 deaths due to heatwaves between 2015 and 2022.

Heatwaves also reduce productivity and affect learning outcomes for children. Studies show that students perform worse during hot school years, and with 15% of government schools lacking functional electricity, rural education is disproportionately affected. Additionally, the absence of adequate cold-chain infrastructure causes significant damage to fresh produce, leading to food losses worth $13 billion annually in India.

According to a World Bank report, India could account for 34 million of the projected 80 million global job losses from heat stress-associated productivity decline by 2030.

In summary, the severe heatwave conditions in Delhi and surrounding regions are a result of a combination of urban heat island effects and broader climatic patterns affecting northern and central India.

(With inputs from PTI)