It's still possible to go to the beach and dip your toes into the Mediterranean in October, though, especially if it's early in the month. The sea temperature runs about 72 degrees Fahrenheit (22 degrees Celsius) in October on the shores of Barcelona.

Yes, you can swim in Barcelona in October, but the experience depends on your tolerance for "refreshing" water. In early-to-mid October, the Mediterranean Sea retains much of the heat from the summer, with water temperatures typically hovering around 20°C to 22°C (68°F–72°F). For many visitors from northern climates, this is perfectly comfortable for a swim. The air temperature is also pleasant, usually ranging from 21°C to 24°C, which makes sunbathing on Barceloneta or Bogatell beach very enjoyable without the sweltering humidity of August. However, as the month progresses, the chances of "Gota Fría" (sudden heavy rainstorms) increase, and the evening air can turn chilly. By late October, the water temperature drops toward 18°C, and most locals consider the swimming season over. If you plan to swim, early October is a "sweet spot" in 2026, offering quieter beaches and clean water, but you should always check the local "beach flags" for sea conditions, as autumn can occasionally bring stronger swells and currents to the Catalan coast.