What is a marine heatwave and how does it affect us?

June 2026 was the hottest June for our oceans ever recorded in western Europe, according to data from Copernicus. Around the UK, waters were much warmer than average – and in some places the warmest ever recorded for the time of year. Now, the UK’s seas are on the brink of a rare extreme marine heatwave, where water temperatures could rise by 2C or more. While that makes a big difference for fish and ecosystems, for us it's still dangerously cold. Advice from the RNLI is if you get into trouble in the water, float. The best way to float is to tilt your head back with your ears submerged. Try to relax and breathe normally. You can gently move your hands and legs to help you stay afloat if you need to. • Subscribe to ITV News on YouTube: http://bit.ly/2lOHmNj • Get breaking news and more stories at http://www.itv.com/news Follow ITV News on TikTok https://www.tiktok.com/@itvnews?lang=en Follow ITV News on Instagram: https://www.instagram.com/itvnews/ Follow ITV News on Facebook: https://www.facebook.com/itvnews/ Follow ITV News on X: https://twitter.com/itvnews