Sea temperatures off the Costa Brava in Girona province have started June at levels usually seen in mid-summer. In L'Estartit, observer Josep Pascual recorded a surface temperature of 22.3 ºC on 30 May, after the sea near the Medes Islands passed 20 degrees earlier than at any other point in this record series.
The early warming is being tracked closely in the Baix Empordà, one of the main reference points for marine temperature monitoring in Catalonia. Pascual's data shows the water near the Medes Islands first went above 20 degrees on 25 May, then reached 22.3 ºC five days later.
Conditions remained warm at the start of June. On Tuesday, 2 June, L'Estartit recorded 22.6 ºC and Torroella de Montgrí 21.2 ºC in the early hours. Pascual said, "We continue with high temperatures for the season."
The weather helped keep the sea warm. In L'Estartit, the day began with high and mid-level clouds, light winds and very calm seas, with waves of just 0.1 to 0.2 metres. Monday was also sunny, with weak winds and a light southerly breeze in the afternoon. In Torroella, that breeze reached 30 km/h from the south-southeast at 3pm.
The warming is most noticeable in the sea's surface layer. Temperatures could change if winds mix the water and bring colder layers up, but the current readings are still high for early June. The European Centre for Medium-Range Weather Forecasts (ECMWF) also showed a warm anomaly in western Mediterranean sea surface temperatures this week, which matches the local measurements from L'Estartit.
For now, it is better to describe this as a warmer-than-usual sea rather than a marine heatwave. A warmer sea can make coastal nights more humid and muggy, and it can also affect storm intensity if cold air moves in at higher levels. The key question is whether this is a short-lived spell at the end of May and start of June, or a pattern that continues in the coming weeks.
