WaveNet data points to potential marine heatwave around UK coastline
14 May 2025
Latest sea temperature data from Cefas’ WaveNet platform suggests UK waters may be experiencing signs of a marine heatwave, with temperatures in parts of the North Sea and southwest coast well above seasonal averages.
Data from WaveNet – a UK-wide network of wave buoys hosted by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) – indicates that sea temperatures recorded at several coastal locations in May were between 1.2 -2.9 °C higher than average for this time of year, and at one location briefly 4.6°C higher (at Tyne/Tees off the Yorkshire coast).
Sites in the Firth of Forth (near Edinburgh), Dowsing (off the Lincolnshire coast), Southwold and West (Suffolk), South Knock (Thames Estuary), Poole Bay and Hastings (both in the English Channel) and off the Scilly Isles (on the southwest coast) all recorded higher than average temperatures.
Figure 1: Temperatures for Tyne/Tees
The data seems to support a recent rolling brief by the National Oceanography Centre (NOC) which suggests UK waters are experiencing a marine heatwave with sea surface temperatures up to 3°C above the seasonal average.
According to the NOC brief, as of Sunday 4th May, sea surface temperatures (SST) remained 0-1°C warmer than usual for this time of year across the entire region, with anomalies of up to +2°C apparent in the central North Sea and off the coast of East Anglia.
Over the past 40 years sea temperatures in the UK have risen by around 1°C, and overall the number of marine heatwaves has increased by around four per year in recent decades. In June 2023, the seas around the UK experienced a marine heatwave, with sea surface temperatures reaching their highest levels for June since records began in 1850.
Marine heatwaves – prolonged periods of abnormally high sea temperatures – can significantly affect the health of marine wildlife, disrupt ecosystems, and cause economic impacts to industries such as fisheries and tourism.
Figure 2: Temperatures Firth of Forth
Established in 2002, WaveNet, provides real-time information on wave heights and temperatures from a network of wave buoys located around the UK coastline. The data, collected from a variety of third-party platforms and programmes (industry and public sector-funded), give an unprecedented insight into the changing conditions at sea around the UK.
In this recent blog, Cefas and the Met Office discuss how WaveNet data is helping forecasters, local authorities, and scientists to better understand the risks and impacts of climate change on the marine environment and coastal communities.
Figure 3: Temperatures for the Scilly Isles
Figure 4: Temperatures for Gabbard
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