Cornwall Sea Temperature Today

Cornwall’s sea temperature ranges from around 9 degrees Celsius in February to 17 degrees in late August. The annual average is approximately 12 to 13 degrees. Cornwall’s waters are warmed by the Gulf Stream, making them milder than England’s east coast at the same latitude.

August and early September are the warmest months for sea swimming in Cornwall, with water temperatures reaching 16 to 17 degrees. Sea temperatures lag behind air temperatures by about 6 to 8 weeks, so the water is still warm well into September even as air temperatures cool.

From July to September, many swimmers are comfortable without a wetsuit for shorter sessions. Outside these months, a wetsuit is recommended. A 4/3mm suit works well from October to May, while a 3/2mm or shortie is fine for summer. Many locals wild swim year-round.

Sea temperatures vary only slightly between Cornwall beaches on any given day, typically within 1 to 2 degrees. South-facing sheltered beaches like Coverack, Kynance Cove, and Carbis Bay sometimes feel marginally warmer due to less wind exposure. The live data above shows the warmest beach right now.