Ahmedabad: The month of Oct is already past its half-mark, but the city or the state at large is yet to experience even a semblance of the pre-winter chill. The temperatures say it all. Ahmedabad’s maximum temperature has remained above 37°C for the past six days, whereas cities like Rajkot and Bhuj recorded temperatures above 40°C.A study that talks about the long-term climatological change for the region shows a spike in the number of days with high daytime and night-time temperatures. During every decade between 1951 and 2025, the number of days with temperatures of 35°C or above increased by about 2.3, states the study, ‘Spatiotemporal Evolution of Temperature Extremes Across India’s Agro-Climatic Zones’. It also highlights nights getting warmer. Each decade over the study period saw the number of nights with a minimum temperature of 20°C or above rise by 1.5.The study, recently published in the International Journal of Climatology, has been authored by Ashutosh Kumar Misra, Sudhir Kumar Mishra and others from India Meteorological Department (IMD) and Indian Council of Agricultural Research (ICAR).Dr Misra, scientist E in IMD’s Agromat Advisory Services Division, and lead author of the study, said that the team looked at the daily temperatures from 1951 to 2025 for India’s 14 agro-climatic zones – regions grouped by soil, rainfall, and farming type. “The results are for the zones and not for individual states. While Gujarat falls under ‘Gujarat Plains and Hills’ zone, some parts also come under the neighbouring ‘Western Dry Region’ zone,” he said.“For Gujarat Plains and Hills, the coldest night of the year is getting warmer by about 0.17°C per decade, whereas the hottest day of the year is rising by about 0.14°C per decade. Both days and nights are getting warmer. The gap between day and night temperatures has not changed significantly in this zone,” he said, adding that the heat accumulated over the cotton season (April-Oct), calculated from daily temperatures, has increased by about 21.6 ‘heat units’ per decade.“This tells us the season is getting warmer. It does not, by itself, tell us that yields are falling as we did not study crop yields,” said Dr Misra.The temperature rise is significant, if not the highest, when compared to other parts of India, said researchers.Researchers said that if the region is compared with other parts of India, in the Gangetic plains of north India, the hottest daytime temperatures have not risen and have fallen in some places, while nights are warming faster than days. “This is consistent with the effect of heavy irrigation, though we did not test this directly. In the southern and coastal regions, daytime warming has been stronger than night-time warming,” said a researcher.The data comes from a 1° grid (roughly 100km), so it shows regional patterns rather than individual towns or districts. While the study’s purpose was not to examine specific causes, the result of overall warming is consistent with earlier studies on the region, said researchers.The study has focused on how temperature windows affect the dominant crops and yields for regions. Gujarat Plains and Hills have cotton, groundnut and dairy as major produce. According to the study, wheat in the trans-Gangetic plain covering parts of Punjab-Haryana and cotton in the Gujarat Plains and Hills showed significant change in the thermal environment relevant to crop phenology. The researchers, however, pointed out that actual phenological responses are not recorded.
