China — Sea Water Temperature and Annual Ranges

Sea Water Temperature Along the Coast

Places with the Warmest Sea Water Today

The Most Popular Seaside Places

Coastal Seas and Oceans

Water Temperature and Swimming Overview

Water Temperature Trends

China’s coastline stretches from the cold temperate Bohai and Yellow Seas in the northeast down through the East China Sea to the subtropical and tropical waters of the South China Sea. Sea surface temperatures vary widely by region and season. In the far north (Bohai/Yellow Sea) winter water temperatures commonly fall to around 0–5 °C (32–41 °F), rising in summer to roughly 20–26 °C (68–79 °F). In the East China Sea near Shanghai and Zhejiang, winter values are typically near 10–15 °C (50–59 °F) and summer temperatures reach about 24–28 °C (75–82 °F). In the southern coast and island areas such as Hainan and Guangdong, waters stay warm year-round, roughly 20–26 °C (68–79 °F) in winter and 28–31 °C (82–88 °F) in summer.

Swimming Conditions

Swimming is widely permitted but practicality and safety depend on season, location and local conditions. Northern beaches are effectively seasonal and are most comfortable for bathing during late spring to early autumn when sea temperatures exceed about 20 °C (68 °F); outside that window waters are often too cold without thermal protection. Central and southern coasts offer a much longer swimming season and Hainan can support year‑round swimming due to its tropical water temperatures. Regardless of region, swimmers should heed lifeguard instructions and advisories about water quality, jellyfish blooms, rip currents and typhoon impacts; some urban or industrialized bays may close temporarily if pollution levels are high. Lifeguard coverage and public facilities are typically concentrated around popular tourist beaches during the summer months.