This story initially appeared on Bulletin of the Atomic Scientists and is a part of the Climate Desk collaboration.
In the course of the summer time of 2025, Iran skilled an distinctive warmth wave, with daytime temperatures throughout a number of areas, together with Tehran, approaching 50 levels Celsius (122 levels Fahrenheit) and forcing the temporary closure of public workplaces and banks. Throughout this era, main reservoirs supplying the Tehran area reached record-low ranges, and water supply systems came under acute strain. By early November, the reservoir behind Amir Kabir Dam, a fundamental supply of ingesting water for Tehran, had dropped to about 8 percent of its capacity. The current disaster displays not solely this summer time’s excessive warmth but in addition a number of consecutive years of lowered precipitation and ongoing drought situations throughout Iran. Consequently, the capital of Iran is now going through a possible “Day Zero” when faucets may run dry.
The drought shortly disrupted Tehran’s city techniques. With dry soils and excessive evaporation, rivers and wetlands shrank. Falling reservoir ranges led to disruptions in hydropower generation, and water shortages prompted strict saving measures throughout elements of the capital. Amid these escalating pressures, officers warned that the capital metropolis could even have to be evacuated if water provides fail to get better. In November, President Masoud Pezeshkian stated the capital would have to be moved. These cascading impacts uncovered how susceptible Tehran’s infrastructure, economic system, and communities have develop into underneath compounding warmth and drought stress.
These cascading impacts stem from a protracted scarcity of precipitation lately (Determine 1a). Precipitation round Tehran usually peaks between December and April, replenishing reservoirs behind dams earlier than the onset of the dry summer time. Over the previous 5 years, precipitation throughout this moist interval has remained persistently under the long-term climatological baseline, with the 2024-25 season displaying probably the most pronounced and extended deficit throughout all the wet season. When such extended dryness was adopted by an exceptionally sizzling summer time, it amplified hydrological stress throughout the area.
