How do Black Sea water temperatures change between winter and summer?

The water temperature of the Black Sea’s upper layer exhibits significant seasonal variation.1

During the winter, surface water temperatures range from 31 °F (-0.5 °C) in the northwest to approximately 48 to 50 °F (9 to 10 °C) in the southeast. This winter cooling process creates an upper mixed layer that extends to depths of about 160 to 330 feet (50 to 100 meters).1

In the summer, the surface layer warms significantly, reaching temperatures between 73 and 79 °F (23 and 26 °C). While the surface warms, a cold layer remains at approximately 45 °F (7 °C) at depths of 160 to 240 feet (50 to 75 meters), and deeper waters remain unaffected by these seasonal surface changes, maintaining stable temperatures.1