Istanbul sea water cools 10°C as upwelling from strong Poyraz winds

Strong north‑easterly Poyraz winds pushed warm surface water from Istanbul’s coast out to the open sea, allowing cold, mineral‑rich deep water to rise to the surface. This upwelling caused sea‑water temperatures to drop abruptly by about 10 °C, with readings falling from the mid‑20s °C to around 17‑19 °C.

Health officials warned that sudden exposure to the cold water can trigger cold‑shock and severe muscle cramps, especially for children, the elderly and people with cardiovascular conditions. Meteorology Engineer Adil Tek said the wind intensity is decreasing and that sea‑temperature levels should begin to return to normal by early next week as the upwelling subsides. He also noted that the current heat wave is expected to be one of the hottest of 2026, with August projected to be warmer than July and the summer season extending into September and October.