The warm pool of water, which has been off the tip of Cornwall for some time now http://old.wetterzentrale.de/pics/Reursst.gif seems to be surviving the more changeable weather. SST around 18C from Land's End to Scilly, despite a good deal of mixing a in a 5' choppy swell.

Despite fairly brief sunny intervals today, often bright rather than sunny, the water just off the Battery Rocks in Penzance was around 19C, not far below today's maximum air temperature of 20.3C. A cooler night than for some time last night, with a minimum of 11.6C, though it was back to 18C by 09:00.