India’s uneven summer: Cooler, yet scorching | Number Theory

Around 56% of the country breached the 40°C threshold on May 18 and 52% on May 19, against the usual 35% for this time of the year.

On May 19, Delhi’s Safdarjung weather station recorded a maximum of 45.1°C, while Banda in Uttar Pradesh recorded a maximum of 48.2°C -- the highest for any place in India this year. Summer, after a long break, is finally back. However, despite the heat, 2026 remains among India’s coolest summers in recent decades, according to an HT analysis of the India Meteorological Department’s (IMD) gridded temperature dataset.

Children cool off in a small pond near the Yamuna river in New Delhi on Wednesday. (Vipin Kumar/ HT Photo)

India’s uneven summer: Cooler, yet scorching

• Overall, this is the 12th coolest May, 16th coolest summer since 1951...

  The average maximum temperature across India in May 2026 up to May 19 – IMD’s gridded data is available with a day’s lag – is 35.16°C. Despite the recent spike this ranks as the 12th coolest May since 1951, the first year for which comparable IMD gridded data is available. It is also 1.15°C cooler than the 1981-2010 average that IMD uses as the normal baseline. The broader summer period, defined here as March 1 to May 19, has also remained cooler than normal. The average maximum temperature for the season so far is 0.51°C below normal, making it the 16th coolest summer since 1951.
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  But maximum temperatures are inching up again beyond normal levels

  While summer 2026 has been relatively mild overall, several recent days have recorded unusually high maximum temperatures. India’s average maximum moved from the 56th highest on May 16 to 36th highest, 27th highest and 25th highest over the next three days. Temperatures were near normal on May 17 and above normal on May 18 and May 19. Deviations above normal were also seen in the second half of April and the first half of March.
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  The area breaching the 40°C threshold has also expanded above normal levels

  It is not just that India’s average maximum is elevated, the geographical spread of heat is also far above normal. Around 56% of the country breached the 40°C threshold on May 18 and 52% on May 19, against the usual 35% for this time of the year. April 25 was worse off, with 58% of India crossing 40°C compared to the normal 26%. This means that though 32 of the 80 days between March 1 and May 19 recorded above normal maximums, those days saw widespread heat across the country.
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  Which places are experiencing the worst heat?

  In terms of absolute maximum temperatures – this is important at least for outdoor activity in the summer – 49% of India averaged a maximum of over 40°C in the three days ending May 19. Around 3% of the country – covering small regions in Maharashtra, Madhya Pradesh, Uttar Pradesh, and Rajasthan – averaged a maximum of over 45°C. The only places that did not breach the 40°C threshold were the hilly regions in the north, eastern and north-eastern states, and the coastal regions in peninsular India. A comparison with the normal for these three days shows that not breaching the threshold did not mean a usual maximum in all places. For example, the maximum in large parts of Uttarakhand, Himachal Pradesh, and Ladakh in the north and Odisha, West Bengal, and Jharkhand in the east was at least 1°C above normal although such regions did not breach the 40°C threshold. Parts of Himachal Pradesh and Uttarakhand recorded maximum temperatures over 3°C above normal. As expected, in places where the maximum temperature breached the 40°C threshold, a higher upward deviation from normal was relatively more common. Warmer than normal maximum is also expected in the week ending May 28 in most places that experienced warmer than normal maximum in the three days ending May 19, according to IMD’s extended range forecast.