Yes, you can definitely sunbathe in Barcelona in May, but it is "shoulder season" weather, so timing is everything. In May 2026, average daytime highs reach around 22°C (72°F), and the city enjoys about 8 to 9 hours of strong sunshine per day. While the air is warm enough for lying on the sand at Barceloneta or Bogatell beach, the sea remains quite cold (around 18°C/64°F), so most people stick to tanning rather than swimming. The sun's UV index in Spain starts to climb significantly in May, so the grounded "safety rule" is to wear high-SPF sunscreen even if there's a cool Mediterranean breeze. For the best sunbathing experience, aim for the last two weeks of the month when the "summer heat" begins to truly kick in, and try to find a spot on the beach between 11:00 AM and 3:00 PM when the sun is at its highest and most powerful.