Out of the world’s 100 hottest cities, 92 are in India, while 6 are in Thailand and 2 in neighbouring Nepal. As early as April, temperatures in cities such as Delhi, Mumbai, Chennai and Bengaluru have already crossed 40°C. Meanwhile, in Middle Eastern desert Gulf countries, usually considered among the hottest, temperatures are in the range of 20°C to 30°C. So how has India become hotter than desert countries like Saudi Arabia and Egypt? Which of our cities are scorching the most, and how much hotter will it get? Let’s understand in today’s Explainer. Which major Indian cities feature among the world’s hottest 100? Uttar Pradesh has the highest number of hottest cities in India. According to AQI.IN data, as of the afternoon of 23 April, cities like Amethi, Mughalsarai, Varanasi and Ghazipur in Uttar Pradesh recorded temperatures of 44°C. Ratnagiri district in Maharashtra also crossed 44°C. Other districts such as Azamgarh, Jaunpur, Ayodhya, Prayagraj (Uttar Pradesh), Chandrapur (Maharashtra), Birbhum (West Bengal), Buxar and Sasaram (Bihar) are among the hottest, with temperatures touching 43°C. In fact, across the listed states, temperatures are not below 40°C anywhere. In contrast, during April, temperatures in typically hot Middle Eastern locations such as Cairo (Egypt) and Abu Dhabi (UAE) remain in the 20°C to 30°C range. Why is the Middle East cooler while India is hotter? The current heat in India can be understood in three steps: 1. Western Disturbances brought rain in early April To India’s west lies the Mediterranean Sea. From here, moisture-laden winds travel via the Mediterranean and Black Sea, through Iran and Afghanistan, into India, these are known as Western Disturbances. These winds disrupt India’s weather patterns, hence the term ‘disturbance’. At an altitude of about 8–15 km, fast-flowing air currents in the upper troposphere are called jet streams, roughly the same height at which passenger aircraft fly. Normally, jet streams flow in a straight path, but sometimes they bend into a ‘U’ shape. In early April, the jet stream bent into a U-shape and directed Western Disturbances towards north and west India. This caused unseasonal rain, hailstorms in parts of Uttar Pradesh, and a temporary drop in temperatures. 2. Jet stream locked in heat, raising temperatures After rainfall, Western Disturbances weaken, leaving behind a low-pressure void. High pressure then pushes air downward, preventing it from rising and forming clouds. Following the passage of the disturbance, skies cleared rapidly over central and southern India. With no clouds and no incoming cool air, a high-pressure system formed near the surface, increasing heat. In simple terms, the same jet stream that initially brought relief later intensified the heat. Scientists refer to this process as ‘subsidence’. 3. Prolonged heating led to the formation of a ‘heat dome’ With high pressure above and rising temperatures below, cloud formation is suppressed. Clear skies allow more solar radiation to reach the ground, which keeps absorbing heat continuously. This condition is known as a ‘heat dome’, which further intensifies the heat. The Middle East is not permanently cooler than India. Gulf countries remain among the hottest regions globally, but temporary cooler winds in April have reduced temperatures there for now. How does a ‘heat dome’ form, and how long will it last? A heat dome is essentially a high-pressure system about 5 km above the ground that traps hot air near the surface like a lid. The hot air cannot rise and continues to heat up under the sun, creating a prolonged heat spell. This differs from typical heatwaves, where rising hot air can trigger storms or rainfall, providing relief. In a heat dome, an anti-cyclonic condition forms, pushing air downward and heating it further. Skies remain completely clear, and rainfall is suppressed. This situation can persist for several weeks until disrupted by a new Western Disturbance or the monsoon. The hotter the surface gets, the stronger the high-pressure system becomes, making the heat dome self-sustaining. Are Delhi and Rajasthan becoming cooler? Any current cooling in Delhi or Rajasthan is only temporary. According to the India Meteorological Department (IMD), temperatures in Rajasthan are expected to rise significantly in the coming days. A heatwave alert has been issued for eastern Rajasthan until 24 April, with effects likely lasting until 26 April. Western Rajasthan may also experience heatwave conditions. IMD data shows temperatures in Delhi and Rajasthan are already 3°C to 5°C above normal. Occasional dust storms or light showers due to Western Disturbances may bring brief relief of 1–2°C. However, once skies clear, the heat dome is likely to intensify conditions again. States like Uttar Pradesh, Bihar and West Bengal entered the heat cycle earlier this year, which is why they rank high globally at present. Are city structures also responsible for this extreme heat? Yes, urban design plays a major role. Scientists are increasingly discussing not just heatwaves but also the ‘urban heat island’ effect. Cities are filled with concrete roads, tall buildings and glass structures that absorb heat throughout the day. Unlike rural areas where the ground cools quickly after sunset, urban materials release heat slowly, keeping nights warmer, often by 5°C to 7°C. Air conditioners also contribute: while they cool indoor spaces, they expel heat outdoors, raising ambient temperatures by up to 3°C. Experts say India’s temperatures haven’t suddenly spiked; rather, cooler conditions elsewhere have pushed Indian cities higher in global rankings. At the same time, both days and nights are becoming hotter. Why are nights also getting warmer? In February 2026, night-time temperatures across 31 states and Union Territories in India were at least 1°C above normal. In 22 states, they were 3°C to 5°C higher. According to IMD, the number of ‘warm nights’ in Indian cities has increased by 32% over the past decade. Two major reasons explain this: 1. Rising humidity According to the Council on Energy, Environment and Water (CEEW), humidity levels in north Indian plains have increased by 10% over the past decade. Cities like Delhi, Jaipur and Kanpur—once known for dry heat—are now experiencing humidity levels rising from 40% to 50%. Higher humidity prevents sweat from evaporating, disrupting the body’s natural cooling system and making it feel 3°C to 5°C hotter than actual temperatures. 2. Global warming and loss of trees By 2026, the Earth’s temperature has risen by 1.44°C above normal levels. This will mark the 13th consecutive year with global temperatures exceeding 1°C above normal. There is also a possibility of El Niño returning by the end of the year. El Niño refers to the abnormal warming of waters in the central and eastern Pacific Ocean, occurring every 4–7 years and influencing global weather. Reports suggest that by 2027, heat records unseen in the past 100 years could be broken. El Niño may also weaken the monsoon, reducing rainfall in India. According to CEEW, night-time heat acts as a ‘silent killer’. If the body cannot cool down at night, the heart works harder to regulate temperature, increasing the risk of high blood pressure, silent heart attacks or heart failure. It also leads to poor sleep, memory issues, irritability and depression. If April is this hot, how severe will May–June be? According to IMD, if April is already witnessing widespread heatwave conditions, there are no signs of relief in May and June. Between May and June 2026, many parts of India are expected to see more heatwave days than usual. IMD forecasts: Heatwave conditions may persist longer than normal in eastern, central and north-western India. Night-time temperatures may remain 3°C to 5°C above normal nationwide. Regions including Odisha, West Bengal, Tamil Nadu, Puducherry, coastal Andhra Pradesh, Gujarat, Maharashtra and parts of Karnataka are likely to experience above-normal heat. IMD Director General Dr Mrutyunjay Mohapatra stated that north-west and central India may witness significantly more heatwave days—up to 15–20 days compared to the usual 8–10. According to private forecaster Skymet Weather, temperatures in Rajasthan, Gujarat and Delhi-NCR could reach 48°C to 50°C by late May or early June. Some relief may arrive with the monsoon in the second half of June, but early June is expected to remain extremely dry and scorching.
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