Rivers around the world ran low in 2025. The World Meteorological Organization said on September 17 that it was one of the driest years for river discharge in more than three decades, with below-normal flows over 36 percent of global basin area. For farms, hydropower plants and water-hungry industry, from Central Asia to the Americas, that is a cost question as much as a climate one.
The past seven years have produced the fewest rivers with “normal” flows since 1991, according to WMO’s State of Global Water Resources report. In each of those years, basins with normal conditions were a clear minority, between 34 and 38 percent, against an average of 46 percent for 1991 to 2020. The water cycle, the report says, now swings between too little and too much.
A savings account running down
WMO Secretary-General Celeste Saulo described slow reserves such as groundwater, glaciers and seasonal snowpack as the planet’s savings account, a buffer for bad years. “We are depleting that savings account,” she said. Land water storage has been falling since 2014-2016.
Every major glaciated region lost ice for the fourth year running. Glaciers shed 408 gigatonnes of mass in the 2025 hydrological year. Nearly two-thirds of monitored wells showed conditions outside the historical norm, and the balance moved further toward deficit than in 2024.
Saulo added a warning for the months ahead. The strengthening El Niño will raise drought risk in some places and flood risk in others.
Asia and Africa bear the brunt
Over the past five years, Asia and Africa together accounted for at least half of all recorded water-related extreme events and more than 80 percent of the associated deaths. Both are still thinly covered by hydrological observations, even though extremes hit them hardest.
The regional picture is uneven. Across 2021 to 2025, river flows were repeatedly below normal in parts of the Amazon and La Plata basins, North America, Central and East Africa, Central Asia and the Middle East. In 2025 itself, discharge was above normal across South and South-East Asia and parts of northern South America. In Africa the Senegal, Niger, Lake Chad, Orange and Limpopo basins ran high, while the Nile, Congo and Zambezi ran much below normal. Eastern European basins, the Middle East and Central Asia were dry too. Reservoir and lake levels tracked the same pattern, and African lakes were largely far above normal, with Kariba the exception.
Weather in 2025 played a part. It was one of the warmest years on record, a weak La Niña appeared late in the year, and a mostly negative Indian Ocean Dipole influenced rainfall.
Better data, with gaps
The report now tracks 15 hydrological variables, up from three in its first edition in 2021, and country coverage has grown sharply. Dozens of experts from national meteorological and hydrological services, data centres and research institutions supplied observations, model output and satellite data.
“Water respects no borders,” Saulo said. A river basin’s water balance depends on what happens in another country, she noted, and a retreating glacier in one place reshapes supply for people hundreds of kilometers downstream. That is why shared data, standards and early warning matter, in her words.
