The North Sea reached a record-high average temperature of 21.5 degrees over the weekend, according to the KNMI. Records dating back to 1984 show that the water has never been this warm. The KNMI attributed the unusually high temperatures to climate change combined with a high-pressure system that brought sunny, calm weather.The record was measured at the Goeree Light Island, a monitoring platform located roughly 30 kilometers off the coast of Hoek van Holland.