- The South Asian Climate Outlook Forum and the India Meteorological Department predict above-normal rainfall during this monsoon season.
- A wetter monsoon forecast raises concern in Kerala, where recent extreme weather has shifted focus from rainfall quantity to its timing, location, and potential impact.
- Kerala has intensified its early warning systems and grassroots rain monitoring through local gauges and community networks.
As the summer rains pound parts of Kerala, farmers and forecasters search for tell-tale signs of a wetter monsoon ahead. This year, the skies signal cautious optimism: above-normal rainfall is likely across most of South Asia, including large swathes of India, according to the South Asian Climate Outlook Forum (SASCOF-31), released on April 30.
The regional outlook underscores the India Meteorological Department’s (IMD) long-range forecast issued on April 15. Seasonal rainfall is expected at 105% of the period average, with a margin of 5% above or below, IMD has said. Calculated over a 50-year period between 1971 and 2020, the LPA for the southwest monsoon is 87 cm.
India’s four-month-long (June-September) monsoon is a lifeline and delivers nearly 70% of its annual rainfall, irrigating more than half of the country’s net sown area that produces almost 40% of its food.
Cautious optimism
Behind the forecast of a wetter monsoon lies a delicate climate chessboard – a dynamic system of interacting atmospheric and oceanic forces. Neutral conditions in both the Pacific and Indian Oceans, alongside reduced northern hemisphere snow cover, have aligned to tip the scales in favour of a wetter-than-usual season, scientists explained. Yet for Kerala, the gateway of the monsoon, the outlook evokes more concern than comfort of late.
Traditionally, the onset of the southwest monsoon around June 1 is met with anticipation bordering excitement in Kerala. By mid-April, advertisements for umbrella brands bloom across television screens and local newspapers as if taking a cue from the IMD’s seasonal forecast.
Keralites, paradoxically, showed little concern for the content of IMD’s long-range forecasts. “The IMD’s models are primarily designed for the core monsoon region, making them less reliable for peripheral areas like Kerala,” said Vijaykumar P., assistant professor at the Department of Environmental Sciences, University of Kerala, Thiruvananthapuram, talking with Mongabay India. Core monsoon region broadly includes central India and parts of the peninsular plateau.
As the pre-monsoon showers lashed the university botanic gardens and wooded slopes on the fringes of the city, Vijaykumar said the mid-April monsoon outlook is now watched more closely — but with a different lens. The growing unpredictability of localised weather, made worse by climate change, has shifted public attention from national optimism to regional risk. The focus has turned from whether it will rain to how, where, and with what consequences.
Since the catastrophic 2018 floods, which killed about 500 people and displaced 1.4 million, the state has witnessed a string of extreme weather events, including deadly landslides in 2024. The monsoon, always romanticised in popular art culture, is now increasingly associated with risk. However, recent events have heightened the need to read between the lines.
In 2019, an unprecedented mesoscale cloudburst quickly turned into a disaster. Mesoscale weather systems are larger than storm-scale systems, spread out from tens to several hundred miles. A cloudburst denotes an extreme amount of rainfall in a short duration of time. A study led by Vijaykumar reported that rainfall exceeding 50 mm in two hours was reported from many places in August 2019. On the contrary, the 2018 Kerala flood was not caused by cloudbursts over any local area but by accumulated rainfall.
“Even predictions of normal to above-normal rainfall are a cause for concern in Kerala. The crucial questions of when and where such rainfall might occur remain unanswered by these general outlooks,” Vijaykumar said. Ecologists warn that this uncertainty is especially stark in a state marked by mountainous terrain and fragile ecosystems like the Western Ghats.
The science behind the surge
The monsoon in India is a powerful weather system driven by a complex interplay of ocean temperatures, wind circulations, land-sea heat contrasts, and remote influences such as snow cover over the Himalayas and the European mountains. Forecasters at SASCOF-31, a regional platform supported by the World Meteorological Organization (WMO), pored over all these variables to produce this year’s cautiously optimistic outlook.
At the heart of monsoon forecasting lies the El Niño-Southern Oscillation (ENSO), the tropical Eastern Pacific Ocean’s powerful climate see-saw moved by ocean temperatures shifting every two to seven years. El Niño years, marked by the warm phase, tend to suppress the Indian monsoon, and the cold phase, called La Niña years, usually enhances it. But in a neutral year, other large-scale and regional factors play a bigger role, as scientists explain. “Currently, neutral ENSO conditions are prevailing over the equatorial Pacific region,” noted an SASCOF-31 bulletin. “The latest forecasts from various coupled global models indicate that the neutral ENSO conditions are likely to continue during the upcoming monsoon season.”
Another set of pieces on the monsoon chessboard is the Indian Ocean Dipole (IOD), which influences rainfall by warming or cooling parts of the Indian Ocean. During a positive IOD phase, warm waters slosh to the western part of the Indian Ocean, while cold water from the deep ocean is brought up to the surface in the eastern Indian Ocean. During the negative phase, this movement is reversed.
A positive IOD is generally associated with a stronger-than-normal southwest monsoon, and a negative IOD is a weaker monsoon. “At present, neutral IOD conditions are prevailing over the Indian Ocean,” the SASCOF-31 bulletin added. “The recent forecasts from coupled global models suggest that the neutral IOD conditions are likely to continue during the southwest monsoon season.”
Apart from these, the extent of the northern hemisphere’s winter and spring snow cover has a general inverse relationship with the subsequent summer monsoon rainfall over South Asia. “Below-normal snow cover in Eurasia for the last three months may boost Indian monsoon,” IMD noted in its seasonal forecast.While these are some of the large-scale influences on the southwestern monsoon, there are also more local factors that favour a wetter seasonal mean rainfall, explained Abhilash S, head of the Department of Atmospheric Sciences at the Cochin University of Science and Technology (CUSAT).
Besides, there are intraseasonal oscillations, which range from 1–2 weeks to less than a season (90 days), that modulate rainfall on weekly and monthly timescales. They can occur several times from May-October. When they align with the movement of low-pressure systems from the Bay of Bengal or the Arabian Sea, the monsoon can surge. “If internal dynamics — involving low-pressure systems and these oscillations — are favourable, they can lead to more intense activity, especially over central India and the west coast,” Abhilash said.
“A wetter monsoon, coupled with a favourable large-scale phase aligning with synoptic and low-pressure systems, can trigger intense rainfall in specific regions,” Abhilash added. Scientists at the Advanced Centre for Atmospheric Radar Research (ACARR) that he heads keep track of these systems through an observational network, including radar systems, and contribute to rain forecasts.
These scientists have identified more factors at play. “In recent times, during the onset of the monsoon, the Arabian Sea has also become more conducive to the occurrence of cyclones,” Abhilash pointed out. This changing storm pattern is of particular concern to southwestern Indian states like Kerala, as recent studies led by ACARR have pointed out.
This convergence of neutral ENSO conditions, active internal dynamics, and warming seas points to a monsoon that may be wetter but potentially more volatile. As scientists continue to unravel the layers of India’s most vital weather system, the message for Kerala and other vulnerable regions is clear: stay alert, not about what the weather will be but what the weather will do.
Preparing for the downpour
Meanwhile, Kerala is intensifying its preparedness measures. Following the devastating landslides of July 2024 in Wayanad, efforts are underway to clear river channels and stabilise vulnerable slopes before the onset of heavy rains.
In January, Kerala launched the KaWaCHaM system, an advanced weather alert mechanism designed to provide timely information to both authorities and the public. It aims to enhance real-time weather monitoring and early warning dissemination.
In Wayanad’s Meppadi panchayat, the scars of the 2024 landslides remain fresh. In collaboration with the Hume Centre for Ecology and Wildlife Biology, local farmers and environmental groups have established about 300 rain gauges across the district for localised real-time observations. This grassroots initiative aims to collect micro-level rainfall data, enhancing community preparedness for potential rain-related disasters.
“We are increasing the density of observation points, especially on the landslide-prone hill slopes,” said CK Vishnudas, director of Hume Centre and a conservation ecologist. “We are also deploying flood level monitors under bridges. They indicate water levels with three colour codes — green, yellow, and red, indicating progressive flood risk levels. It’s a collective warning system.”
Observations are shared among local people over social media, informing them about the weather outlook and risk factors at different times. Based on these observations, the local farmers said Kottathara Panchayat, which suffered huge losses in the 2019 floods, reported 36mm of rainfall on a single night on May 2 and even higher rainfalls elsewhere.
“We had hailstorms, and many farmers have lost vegetable crops,” said Joshy Paul, a local farmer and project manager with the national NGO Swayam Shikshan Prayog (SSP) in Wayanad. The NGO that promotes localised climate adaptation through women’s self-help groups is now training volunteers in all the wards of the Kottathara panchayat to participate in rain forecasting. “Soon, we will have to learn how to do farming in alignment with the rainfall patterns,” he said.
Despite the challenges, the monsoon season also brings joy and cultural vibrancy where the farmers and adivasis celebrate the rains. The Splash 2025 Monsoon Carnival in Wayanad, a tourism initiative by the government, is scheduled from July 11-14.
As Kerala continues to grapple with the dual nature of the monsoon, a children’s song celebrates the magic of the monsoon: “mazha mazha mazha payyunnu, puzhayum vazhuyum nirayunnu…” (Rain, rain, rain, it pours and fills the river and the street…)
Read more: [Commentary] Is Indian monsoon turning into a string of extreme weather events?
Banner image: Rainfall in Kerala. The convergence of neutral ENSO conditions, active internal dynamics, and warming seas points to a monsoon that may be wetter but potentially more volatile. Image by Paul Varuni via Wikimedia Commons (CC BY 2.0).
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