Kathmandu, September 21, 2026 .Rainfall activity is expected to increase in Nepal over a five-day period starting this coming Thursday. Various weather forecasting models indicate rainfall across many regions of Nepal from Thursday (Ashwin 8) to Monday (Ashwin 12), with a likelihood of heavy rain, particularly on Friday and Saturday.

Meteorologists state that projections from various models—including the European Centre for Medium-Range Weather Forecasts (ECMWF), the US Global Forecast System (GFS), and the German Weather Service's ICON model—suggest that a weather system developing over the Bay of Bengal will reach Nepal next week. However, there is currently no consensus among the models regarding exactly which regions will receive the most rainfall or the specific amounts expected.

Dr. Binod Pokharel, an Assistant Professor at the Central Department of Hydrology and Meteorology at Tribhuvan University, noted that an analysis of various forecasting models shows a strong likelihood of rain in Nepal from Thursday through Monday. "A low-pressure system is forming. Since it is projected to reach Nepal, there is a possibility of heavy rainfall. While rain is expected over four to five days, there is a high probability of heavy downpours on two of those days," he said. "However, the rainfall may not be uniform across the country; it could be concentrated in specific areas."

Meanwhile, the Department of Hydrology and Meteorology—which generates its own forecasts using mathematical weather prediction models alongside data from existing systems—issued a statement on Sunday evening. The department noted that while the low-pressure system is expected to bring rain to Nepal, it is not yet possible to definitively assess the level of risk or the potential impact. According to meteorologist Hari Prasad Dahal of the Department of Hydrology and Meteorology, Nepal is currently experiencing the partial influence of both monsoon winds and westerly winds. The monsoon trough (low-pressure line) is positioned south of its average location. "A low-pressure area is developing over the North Andaman Sea and its vicinity. There is a possibility that it will intensify and move in a west-northwesterly direction," he said. "However, the system has not yet fully developed. Therefore, it is impossible to predict with certainty exactly which areas will receive rainfall or how much. The system's trajectory and model projections could change in the coming days."

Dr. Dharma Raj Upreti, Executive Chief of the National Disaster Risk Reduction and Management Authority, stated that the low-pressure system is likely to impact Nepal in some form. "Open-source models indicate rainfall in Nepal. The India Meteorological Department has also predicted that it will move towards the northwest," he said. "Rainfall is possible in Nepal, but the specific direction and extent of the impact remain to be determined. The recent statement was issued following a discussion between us and the Department of Hydrology and Meteorology; they are expected to provide updated projections by Monday evening or Tuesday."

Why is the system forming in the Bay of Bengal significant?
According to the India Meteorological Department, the low-pressure area developing over the North Andaman Sea and the east-central Bay of Bengal is moving in a west-northwesterly direction. It is projected that this system will intensify into a 'depression' on Monday and further strengthen into a 'deep depression' on Tuesday, eventually reaching the coastal regions of southern Odisha and northern Andhra Pradesh. Meteorologists estimate that rainfall in Nepal could increase if the water vapor from this system interacts with the westerly atmospheric system affecting the country. Dr. Binod Pokharel, an Associate Professor at the Central Department of Hydrology and Meteorology at Tribhuvan University, stated that there is a strong possibility of increased rainfall due to the convergence of the system originating from the Bay of Bengal and the westerly system, which would enhance the flow of water vapor towards Nepal.