India’s monsoon turns deadly as climate change, atmospheric patterns and unstable mountains drive extreme rains
Extraordinary downpours and a rare clash between the monsoon and westerly disturbances have flooded large parts of India, killing hundreds and inundating towns from the Himalayas to the plains.
Heavy monsoon rains have affected roughly half of India, causing widespread floods and landslides that officials say have killed hundreds and inundated towns and villages across multiple states.
The India Meteorological Department (IMD) says some areas of Punjab, Haryana and Rajasthan received more than 1,000% of their normal 24‑hour rainfall totals in places, while rainfall in northwest India between Aug. 28 and Sept. 3 was about 180% above average and the south recorded 73% above average for the period. Punjab is experiencing its worst deluge since 1988, and forecasters warn more heavy rain is likely across large parts of the country this week.
Researchers and meteorologists say a combination of climate-driven changes, unusual atmospheric interactions and mountain instability explain why the monsoon has produced such concentrated and deadly downpours this season. A primary factor is that a warmer climate has increased moisture in the air over the Indian Ocean and Arabian Sea, providing more fuel for intense rain when conditions align.
Historically, the Indian monsoon delivered steady rain spread across the June–September season. In recent years, however, specialists have documented a shift toward rainfall concentrated in short, intense bursts separated by dry spells. In mountainous regions, this pattern has manifested as cloudbursts — sudden, very heavy rainfall over a small area — that trigger rapid runoff, flash floods and landslides. Cloudbursts were a main cause of flood and landslide damage in Himalayan states such as Uttarakhand and Himachal Pradesh and in Indian-administered Kashmir during the first week of August.
In the northwestern plains, meteorologists say the extreme August rains resulted chiefly from an interaction between the monsoon circulation and one or more westerly disturbances, low-pressure systems that form over the Mediterranean and travel eastward. Westerly disturbances carry cooler air aloft that, when it encounters warm, moisture-laden monsoon air near the surface, can produce intense convective activity and prolonged rainfall.
"It's the result of a rare 'atmospheric tango' between the monsoon and the westerly disturbance," said Akshay Deoras, a research scientist in the Department of Meteorology at the University of Reading. "Think of the monsoon as a loaded water cannon, and western disturbances as the trigger."
The IMD has confirmed that clashes between the monsoon and westerly disturbances were a key driver of the sustained extreme rainfall in northern India and other parts of the country. Meteorologists say such interactions are uncommon during peak monsoon months because westerly disturbances typically migrate northward; this year they moved unusually far south.
Scientists link that southward shift to changes in the jet streams, the high‑altitude, fast‑moving air currents that help steer large‑scale weather systems. Research indicates global warming can make jet streams more meandering or "wavier," altering the paths of systems such as the subtropical jet and allowing westerly disturbances to penetrate farther south than usual. Those altered wind patterns have been associated with extreme weather events in other regions as well.
Mountain instability has amplified impacts where heavy rain fell in upland areas. Rapid melting of glaciers and snowfields, weakening permafrost and increased rainfall at elevations that previously received snow are all cited as factors that can destabilize slopes. Such instability can produce landslides, block river channels and cause glacial lakes to burst, releasing sudden downstream floods.
"We are seeing entire snowfields melting within a day or two when rains fall on them and the huge quantity of water gushes down as floods," said Jakob Steiner, a geoscientist at the University of Graz.
Scientists are still investigating specific events, but they note several mechanisms that can produce floods even without localized heavy rain: the failure of glacially dammed lakes, the sudden release of water from saturated underground lenses, and landslides that form temporary dams then breach catastrophically. In many cases, downstream areas in India and Pakistan have suffered devastating flooding after such mountain processes were triggered upstream.
Human activity has compounded the natural drivers of flood risk. Urban expansion and development have encroached on floodplains and traditional river courses, while highways, hydropower projects and other construction can weaken mountain slopes or alter drainage. Municipal drainage systems and river embankments in some areas remain unrepaired, and plastic waste blocking waterways has reduced the capacity of urban drains to carry away stormwater.
Officials and experts have urged repair of embankments, improved urban drainage and better enforcement of zoning to keep settlements out of river channels and floodplains, but implementation has varied across states. Authorities in affected regions have been engaged in rescue and relief operations as rivers swell and communities are cut off. More rain in the forecast has complicated efforts to assess damage and stabilize embankments.
The season's extreme events reflect both short‑term atmospheric dynamics and longer‑term climate trends, scientists say. While specific weather patterns determine where and when rains intensify, rising sea and air temperatures increase atmospheric moisture and can amplify the intensity of individual storms. Researchers emphasize that understanding the interaction among changing jet streams, westerly disturbances and the monsoon, together with the vulnerabilities created by mountain melting and land use, is essential for improving forecasts, early warnings and disaster preparedness.
The IMD and state agencies continue to monitor weather systems and issue advisories. Rescue operations, sheltering and relief distribution are ongoing in the hardest-hit districts as authorities seek to limit further loss of life and property while assessing the full scale of the season's damage.