For more than a century, India’s lifeline, the monsoon has been shifting in unpredictable ways. New research shows that rainfall patterns across the country have changed dramatically since the 1960s, altering when, how long, and how hard it rains.
Every June, dark clouds roll in from the Arabian Sea, carrying the promise of life to millions. The summer monsoon brings nearly 80 percent of India’s annual rainfall. Water that sustains its farms, fills its rivers, and feeds its cities. But as the rains grow erratic, so does the future of those who depend on them.
The study, published in 2025 by researchers from IISER Bhopal and Geo Climate Risk Solutions, analyzed 123 years of daily rainfall data from 1901 to 2023. It found sharp differences before and after 1960, a period identified as a turning point in India’s monsoon behavior.
The study highlights a sharp decline in the total volume and duration of rainfall since the 1960s, even as the intensity of daily downpours has risen pointing to a shift toward shorter but more extreme rain events.
Uneven Across Country
The findings show that changes are uneven across the country.
In the North East, both rainfall volume and intensity have risen in long-duration spells, exposing nearly 37 percent of the region to severe high-volume, high-intensity events. This makes the region more vulnerable to river flooding and landslides.
Central India has seen a rise in short-duration, intense events. The study described these as “low volume–high intensity extremes,” which increase the risk of flash floods and urban drainage failures.
The Western Ghats show a different trend. Rainfall volumes have declined, but bursts of high-intensity rain remain frequent. “This indicates declining rainfall volumes but persistent short bursts of intense precipitation,” the researchers noted. These patterns raise the risk of localized landslides and floods without long-term water recharge.
In the South Eastern Peninsular region, both moderate and long-duration spells have intensified. Western India shows a similar pattern, with a rise in long-duration heavy rainfall. In contrast, parts of the Himalayan region are experiencing more variable rain spells, contributing to higher flood and glacial lake outburst risks.
Supporting the study, the recent IMD data from 2025 also underlines this unevenness. The southwest monsoon season ended with eight percent above-normal rainfall nationwide, but nearly 20 percent of India’s districts recorded deficits. Deoria in Uttar Pradesh had the steepest shortfall at 87 percent, while Ladakh saw 342 percent excess rain.
Regionally, the east and northeast recorded a 20 percent deficit, the second-lowest monsoon since 1901.
IMD chief Mrutyunjay Mohapatra said, “Rainfall over east and northeast India has been deficient in many years in recent times. There is a trend that rainfall over this region is decreasing since 2020.”
The IMD reported that east and northeast India saw their second-lowest rainfall since 1901, continuing a 20-year decline. In, northwest and central India experienced surpluses of 27 percent and 15 percent, respectively, the highest in more than two decades.
Himalayan states like Himachal Pradesh and Jammu and Kashmir faced repeated cloudbursts and flash floods, while Punjab witnessed its worst flooding in decades. These regional extremes reinforce the study’s finding that the monsoon is shifting toward shorter, more intense events rather than steady rainfall.
At the same time, northwest India received 27 percent above-normal rainfall, the highest since 2001, while Central India recorded a 15 percent surplus. The southern peninsula also ended with nearly 10 percent more rainfall than normal.
Despite the surplus, the season was marked by cloudbursts, landslides, and floods across several states, echoing the new study’s warning that short, intense rainfall bursts can bring disasters even when the overall rainfall appears healthy.
IMD data shows the human toll of these changing rainfall patterns. Between June and September, extreme weather events claimed at least 1,528 lives across India.
Of these, 935 deaths were caused by floods and heavy rains, 570 by lightning and thunderstorms, and 22 by heat waves. Madhya Pradesh recorded the highest toll at 290 deaths, followed by Himachal Pradesh with 141, Jammu and Kashmir with 139, Maharashtra with 135, and Uttar Pradesh with 201 fatalities. Most of these deaths were linked to either intense rainfall or lightning strikes, underscoring how erratic monsoon behavior is directly affecting people’s lives.
Experts say these changes reflect a deeper shift in how the Indian monsoon behaves under a warming climate.
Dr. Rajeevan Madhavan Nair, former Secretary of the Ministry of Earth Sciences, explained that while the overall amount of rain India receives each year has not shown a clear long-term trend, the regional differences have become sharper.
“While the total rainfall across India has not shown a clear long-term trend on a national average, there are large spatial variations,” Dr. Nair said. “Some regions like Kerala, parts of Northeast India, and East Central India are receiving less rainfall during the monsoon season. In contrast, areas such as North Karnataka, Maharashtra, and Rajasthan have seen an increase.”
He added that the character of rainfall itself is changing. The number of heavy rain events, where more than 150 millimetres fall in a single day, has grown steadily over the decades.
“The frequency of extreme rainfall events, especially those exceeding 150 millimetres in a day, is also rising , by about two events every decade,” Dr. Nair said.
This increase in intensity is reshaping how and when India gets its rain. Instead of steady rainfall spread across the season, more precipitation now falls in shorter, intense bursts.
“Nearly half of the season’s rainfall now falls within just 20 to 30 hours, covering only about 20 percent of the monsoon period,” Dr. Nair explained. “The remaining 50 percent of rainfall occurs as light to moderate rain over 80 percent of the time. This uneven distribution affects water availability, soil health, and crop productivity.”
Short, moderate, and long spells
To understand the shifts, researchers divided monsoon rain spells into three types. Short spells last up to 10 days. Moderate spells last 10 to 30 days. Long spells stretch beyond 30 days.
Each type has distinct impacts. Short spells can trigger flash floods. Moderate spells play a role in groundwater recharge. Long spells affect river flooding and waterlogging.
The study found that short and intense bursts are becoming more frequent. Longer, steadier spells are declining in several regions. “Short-duration rainfall events are undergoing distinct spatial transformations,” the study reported. Central and eastern India are seeing more intensity, while coastal and Himalayan areas are seeing declines.
“Nearly half of the season’s rainfall now falls within just 20 to 30 hours, covering only about 20 percent of the monsoon period. The remaining 50 percent of rainfall occurs as light to moderate rain over 80 percent of the time. This uneven distribution affects water availability, soil health, and crop productivity,” Dr. Nair said.
A key focus of the research was compound extremes, when high intensity and high volume occur together in the same spell. Most previous analyses looked at volume and intensity separately. This study combined them, offering a clearer view of flood risks.
The team developed two indices. High Volume–High Intensity (HVHI) events occur when both measures rise together. Low Volume, High Intensity (LVHI) events occur when intensity rises but total volume falls.
In Central India, nearly 27 percent of the region is now exposed to severe HVHI events during short spells. More than half the region also faces LVHI extremes.
In the North East, about 37 percent of the area is affected by severe HVHI events of long duration. In the Western Ghats, nearly 60 percent of the region shows exposure to LVHI extremes. Western India records one of the strongest HVHI signals, with 62 percent of the area affected, especially since the 1990s.
“These compound extremes have critical implications for flood risk, water management, and infrastructure design,” the study said.
Climate Change Connection
The study links these shifts to larger climate signals. Warmer sea surface temperatures in the Indian Ocean have altered the contrast between land and sea, a key driver of monsoon flows. Rising moisture in the atmosphere is fueling heavier downpours.
Other researchers have reported similar findings. A 2017 study noted a threefold rise in heavy rainfall events over Central India since the 1950s. Another study documented a fall in total seasonal rainfall even as extreme events increased.
The authors wrote, “Recent decades show a paradox. While total rainfall has declined in many regions, the frequency of intense, short-lived events has increased.”
These shifts have direct effects on farming, water supply, and disaster management.
The rising toll from floods and lightning underlines the growing mismatch between rainfall totals and ground realities. Even with an overall rainfall surplus, India saw widespread destruction, roads washed away in Himachal Pradesh, crops damaged in Madhya Pradesh, and homes flooded in Punjab and Maharashtra. This suggests that rainfall statistics alone no longer capture the real risks of the monsoon.
Farmers rely on steady rainfall to match crop calendars. Longer dry periods broken by sudden downpours disrupt planting and irrigation. Groundwater recharge suffers when rainfall comes in short bursts instead of sustained spells.
Cities face drainage failures when intense rain overwhelms stormwater systems. In the Himalayas, more erratic spells have increased flood and landslide risks. In the Western Ghats, reduced volumes but high-intensity bursts put stress on river systems and ecosystems.
The study stressed the need for local strategies. “Region-specific adaptation strategies and hydrological models must incorporate compound rainfall behaviour,” it said. Measures include strengthening drainage, expanding storage, and adjusting agricultural practices.
A Global Trend
The Indian results are part of a wider pattern. East Asia, North China, and the Sahel region have seen similar rises in short, intense rainfall. In Europe, extreme rainfall has become more frequent at higher latitudes.
Globally, long dry spells are increasingly interrupted by heavy downpours. Scientists link these changes to shifting atmospheric circulation and human-driven warming.
“These international comparisons offer a valuable context for assessing changes in rain spell behaviour in India,” the authors wrote.
The researchers acknowledged limits in their work. The analysis used ground-based rainfall data, which may not fully capture patterns in areas with few monitoring stations, such as the Himalayas and North East.
The study classified rain spells using national thresholds, which may not always reflect local flood risks. It also focused only on rainfall data, not direct flood damage or socio-economic losses.
The team suggested that future work link rainfall data with river flow, land use, and disaster records. This could improve flood risk assessments and help urban planners and infrastructure designers.
road ahead
Despite these limits, the study provides one of the most detailed long-term assessments of India’s monsoon shifts. It shows the need to track intensity and volume together, not separately.
The authors concluded, “By advancing the understanding of compound rainfall extremes, this study aims to inform risk-sensitive planning and the development of early warning systems.”
With India’s growing cities, rising water demand, and the monsoon becoming less predictable, these findings underline the urgency of building resilience.
“Developing multi-hazard early warning systems and climate-resilient infrastructure requires region-specific strategies that account for the compound nature of rainfall extremes,” the study said.
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