Hotter, wetter summer monsoon forecast underscores urgency of early warnings

Meteorological agencies across the world have predicted a high probability of a wetter-and-hotter-than-normal summer monsoon for most of South Asia in 2025. That is likely to intensify the risks of water-related disasters in the Hindu Kush Himalaya (HKH) terrain spread across the eight South Asian countries of Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan – surmise experts from  the International Centre for Integrated Mountain Development (ICIMOD) in their HKH Monsoon Outlook 2025.

The summer monsoon, between June and September, is the major source of precipitation in the HKH region with significant impacts on the hydrology of its river basins, which form the lifeline of nearly two billion people in the region.  While a good monsoon is essential for replenishing these river systems, above-normal precipitations can expose the region to high risks of disastrous flash floods and landslides along the mountainous terrains and riverine floods in the plains. Historical records of floods in the region show that 72.5% of the total number of flood events recorded between 1980 and 2024 occurred during the summer monsoon season.

On the other hand, rising temperatures can accelerate cryosphere melting, contributing to short-term increases in river flow or ‘discharge’ and heightening the risk of glacial lake outburst floods, and in combination with wetter monsoon can enhance heat stress and cause waterborne disease outbreaks.

Pooling together the analyses of global and regional meteorological bodies like the 31^st South Asian Climate Outlook Forum (SASCOF-31), APEC climate center (APCC), International Research Institute for Climate and Society (IRI), Copernicus Climate Change Service (C3S), along with those from various national agencies, the Outlook predicts temperature at above-normal level in almost all eight countries with an estimated mean summer temperature anomaly ranging from 0.5°C to 2°C above-normal. High probability of above-normal precipitations is predicted for over most of India, Nepal and Pakistan. While Afghanistan, Bangladesh, Bhutan and Myanmar are likely to receive near-normal levels of rainfall, normal to above-normal precipitations are also predicted for the Tibet Autonomous Region (TAR) of China.

Reflecting on these predictions, Arun Bhakta Shrestha, Senior Advisor at ICIMOD, reasserted the exacerbating vulnerability of the HKH region to increasing climate anomalies and cascading climate-induced disasters, “The tragic loss of lives and extensive damage during the September 2024 floods in Kathmandu Valley is a stark reminder of the rising climate threats in the region. It is a slice of the future staring us in the face. With projections across –the board indicating increasing monsoon precipitations and a shift toward more extreme events, there is an urgent need to revamp disaster preparedness and invest in improved forecasting and impact-based early warning systems across the region.”

Extreme weather events happen on the scale of a single day, while the nature, magnitude and extent of their adverse effects vary widely over physiography and across socioeconomic groups. Forecasting these events with accuracy calls for spatially and temporally localised signals of climatic anomalies. Simultaneously, such forecasts also need to account for exposure and/or vulnerability, translating the physical hazard characteristics into socioeconomic consequences.

However, given the dual dearth of short-term meteorological prediction capability and commensurate investments in the HKH, longer-term forecasts, such as the ones compiled in the HKH Monsoon Outlook, are critical for building insights into the prospective seasonal conditions at large. According to Sarthak Shrestha, Remote Sensing and Geo-Information Associate at ICIMOD, “Sharing this information timely is important from the point of disaster preparedness. Last year’s floods and landslides were an eye-opener for the strong need for early action and coordinated response across the region.”

In view of the rising frequency and aggravating severity of extreme weather events in the region, there is a growing consensus among regional meteorologists and disaster risk management experts on the need for impact-based forecasting of meteorological parameters and events. In tandem, ICIMOD has developed a suite of toolkits for forecasting precipitation, temperature, and river discharge up to two to ten days in advance, for Bangladesh, Bhutan, Nepal and Pakistan.

“These tools are already being used by the hydro-meteorological departments of the governments of Bangladesh and Nepalto generate their flood bulletins. The Red Cross and several municipalities across Nepal use these bulletins for anticipatory actions.  The Benighat Rorang Municipality in the Bagmati Province of Nepal, for example, used these early warnings during the September 2024 floods to close schools in advance and keep almost 17,000 students safe. Our next step is to use these tools for impact-based forecasting,” says Manish Shrestha, Hydrologist at ICIMOD.

According to Saswata Sanyal, Manager, Disaster Risk Reduction Intervention, ICIMOD, “Our Community-Based Flood Early Warning Systems (CBFEWS) have proven to be life-saving tools, particularly in Nepal’s southern plains, where municipalities have adopted them to strengthen flood response. The demonstrated success of these systems has attracted interest from neighbouring countries such as Bangladesh, Bhutan, and India, to test and replicate similar approaches in their watersheds toward end-to-end warning and last-mile connectivity. This underscores the vital role of proactive, community-centered approaches in building resilience to climate-induced disasters. At ICIMOD, we aim at converting warnings to actions – empowering communities before the disaster strikes.”