Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
This story is original appeared on Bulletin of the Atomic Scientists It is part of Climate Office cooperation.
During the summer of 2025, Iran experienced an exceptional heat wave, with daytime temperatures in several areas, including Tehran, approaching 50 °C (122 °F) and forcing… Temporary closure From public offices and banks. During this period, the main reservoirs feeding the Tehran region reached record low levels, and Water supply systems were under severe pressure. By early November, the level of the reservoir behind the Amirkabir Dam, Tehran’s main source of drinking water, had fallen to about 1,000 cubic metres. 8 percent of its capacity. The current crisis reflects not only the extreme heat this summer, but also several consecutive years of low rainfall and persistent drought conditions across Iran. As a result, the Iranian capital now faces a potential “day zero” when the taps run dry.
Drought quickly disrupted Tehran’s urban systems. With dry soil and high evaporation, Rivers and wetlands have shrunk. Low tank levels resulted in Disturbances in hydroelectric power generationWater shortages have led to strict conservation measures in parts of the capital. Amid this mounting pressure, officials have warned that the capital may break even They must be evacuated If the water supply fails to recover. In November, President Masoud Pezeshkian said the capital would do so It must be transferred. These cascading impacts have revealed how vulnerable Tehran’s infrastructure, economy and communities are under the weight of worsening heat and drought.
These cascading effects stem from prolonged rainfall deficits in recent years (Figure 1a). Rainfall around Tehran usually peaks between December and April, replenishing reservoirs behind dams before the onset of dry summer. Over the past five years, rainfall during this wet period has remained consistently below the long-term climatological baseline, with the 2024-2025 season showing the most pronounced and long-lasting deficit across the entire rainy season. When this prolonged drought was followed by an exceptionally hot summer, it exacerbated hydrological stress throughout the region.
