Never since records began more than 40 years ago has the average sea surface temperature been as high as in April. The average temperature usually rises until March and then starts to fall, but this year it has remained around 21 degrees since mid-March.
This is well above the normal values. In 1982-2011, the average fluctuated between 20 and 20.7 degrees at the end of April, according to statistics from the US National Oceanic and Atmospheric Administration (NOAA). In early April, the previous record was also broken – 0.1 degrees higher than the previous extreme year 2016.