The Mediterranean Sea is in the grip of an exceptional marine heatwave this week, with surface waters in some areas edging towards 30°C — a level not seen since the infamous 2003 heatwave.
According to Mercator Ocean International, part of the EU’s Copernicus Marine Service, July 2025 already recorded remarkable anomalies. The average surface temperature across the Mediterranean reached 26.68°C, covering 95% of its waters, with 40% of the basin heating by at least 2°C above the seasonal average.
In parts of the western Mediterranean near Spain, and in the central basin around Italy, sea surface temperatures have already breached the 30°C mark, more than 5°C above normal. Such extremes are destabilising marine ecosystems, disrupting reproduction cycles, and threatening species from seagrass meadows to tuna populations.
The surge in sea temperatures follows a sequence of back-to-back marine heatwaves in recent years, each linked to climate change. The Mediterranean has been warming at an accelerated rate, with scientists warning it is now one of the fastest-heating seas in the world. In August 2024, median surface temperatures reached 28.9°C in some parts of the basin — around 2.7°C above normal — peaking at 30.8°C off the Côte d’Azur.
This summer’s marine heatwave compounds the effects of intense land-based heatwaves sweeping across Europe, with southern France among the worst affected. Scientists note that both Europe and the Arctic are warming more than twice as fast as the global average, intensifying extreme weather events on land and at sea.
For Monaco and the surrounding Riviera, the trend carries particular significance. Warmer waters threaten the delicate balance of marine biodiversity in the Pelagos Sanctuary, while also impacting local fisheries and coastal economies. With water temperatures still climbing, the coming days could see new records — and stark reminders of the Mediterranean’s vulnerability in a rapidly changing climate.
Stay updated with Monaco Life: sign up for our free newsletter, catch our podcast on Spotify, and follow us across Facebook, Instagram, LinkedIn, and Tik Tok.
Photo credit: Cassandra Tanti, Monaco Life