Guwahati: Northeast India is experiencing a rise in intense one-day rainfall alongside more frequent dry spells, pointing to increasing instability in the region’s monsoon, according to a 52-year study of India’s climate extremes.
The study, which analysed weather data from 1971 to 2022, found that the Northeast was the only region in India to show a clear, statistically significant increase in extreme one-day rainfall during the period. At the same time, the region has experienced more frequent dry spells and drought conditions.
The findings are part of a study titled ‘Evolution of Climate Extremes Over the Indian Subcontinent Using a Revised CEI’, published in the peer-reviewed International Journal of Climatology.
The research was conducted by scientists from the India Meteorological Department (IMD) and the National Centre for Medium Range Weather Forecasting (NCMRWF).
The study covered Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura, Arunachal Pradesh and Sikkim as part of its assessment of the Northeast.
“The northeast is the one region swinging between extremes, heavier single-day downpours on one side and longer dry spells on the other. That combination points to a more unstable monsoon, and it calls for both flood preparedness and drought planning,” said M Rajeevan, co-author of the study, professor at Atria University, Bengaluru, and former secretary of the Ministry of Earth Sciences.
Lead author Thota Mohan of the NCMRWF said the Northeast stood apart from the broader pattern of increasing heat and drought seen across much of India.
“The northeast is the only part of the country where we see a clear rise in short, intense one-day rainfall, even as dry spells lengthen. It stands apart from the heat-and-drought story that dominates the rest of India,” Mohan said.
The researchers combined seven climate hazards, including daytime heat, humid heat, heatwave severity and drought, into a revised India Climate Extremes Index. The analysis was based on 52 years of observations from the IMD, with trends assessed using the Mann-Kendall statistical method.
The researchers link the increase in extreme one-day rainfall in the Northeast to factors including a warming Bay of Bengal, increased atmospheric moisture and the region’s complex terrain.
The combination of heavier downpours and longer dry periods could create greater challenges for the region, where both floods and water stress already affect agriculture, infrastructure and communities.
The study recommends strengthening flood preparedness and improving management of rainfall variability as priorities for the Northeast. It calls for a cross-sectoral response involving agriculture, water management, health and infrastructure, along with more detailed, localised monitoring.
The researchers cautioned that regional averages can obscure localised extremes that drive flood and drought risks. They also proposed using the revised climate extremes index as an operational tool that agencies could use annually to identify areas where climate-related stress is increasing.
The study was authored by Thota Mohan, M Rajeevan, Smrutishree Lenka, Kondapalli Niranjan Kumar, P Rohini and O P Sreejith. It was published in the International Journal of Climatology in 2026.
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