UK sea temperatures continue to skyrocket after Spring heatwaves
22 May 2025, 17:01
Temperatures in the sea surrounding the UK have soared after warm temperatures this Spring, with some areas reaching 4C higher than normal.
Listen to this article
Loading audio...
Experts are worried the significant temperature raise could have implications for marine wildlife, as well as people swimming.
The marine heatwave has lasted much longer than average. Marine heatwaves typically tend to last between two and three weeks - this heatwave is currently standing at two and a half months.
Starting to warm in March, sea temperatures in April and May were the highest recorded since records began 45 years ago.
The areas most affected are around the west coast, particularly around Cornwall and Ireland, where temperature changes of +4C have been recorded in some areas.
Read More: Spring heatwave to break UK records for April and May
The sunny and largely settled conditions this Spring haven't just been over land ☀️
— Met Office (@metoffice) May 22, 2025
Combined with weak winds and waves, the conditions have warmed sea surface temperatures to record levels for the time of year, leading to a prolonged marine heatwave
Read more in our blog 👇
The average temperature rise across the whole of the west coast is +2.5C, and temperature changes of +2-3C have been recorded in Scottish waters.
The east coast is cooler, varying between +1C and +3C, but this is due to cooler waters flushing south from the North and Celtic Seas.
Water from the North Sea has travelled south and brought temperatures on the east coast down with it, but
The temperature change is measured against temperatures on an average day between 1982-2011.
Scientists expect 2025 to be one of the hottest years on record for air temperature.
A marine heatwave is defined as a surge in average temperature that exceeds 5 days. In the UK, the threshold for a marine heatwave in May is 11.3C.
On May 19, the average sea surface temperature reached 12.9C.
It’s unclear exactly how these temperature changes will affect marine life long-term - but for now, the temperature threshold marine life can no longer tolerate has not been reached.
Increased temperatures could cause harmful blooms of algae however, which can impact the biome and food chain of affected areas of water.
