May is one of the best months of the year in terms of weather in Barcelona You can see from the weather log written below, most of the time it will be sunny and warm in May. This will be a good time to walk around and explore Barcelona with good light and light warm breezes that are very pleasant. It’s early in the season for sunbathing but you will find people at the beaches now. The beaches are a lot less crowded than peak season. You will need sun protection especially during the mid part of the day.