Barcelona is a great destination whether you're going for you first time or the tenth, there is always a reason to come back. However, with Barcelona time is always of the essence, if you wait too long you'll be sweating uncontrollably under the August sun, if you want to avoid the crowds you'll also be avoiding the beach because its only empty during the winter. Some times are better than others to visit this wonderful city, but you shouldn't wait you should start packing and head to Barcelona right now!
The Sunny Side
Barcelona has notoriously great weather and a beach to go along with it. As mentioned before sometimes the sun can become unbearable but right now the weather is just about as perfect as anyone could ask for. From now until the beginning of the summer season the weather usually sits in mid-70s F/mid-20s C rarely breaking 80 F/26 C. The other great thing is that the rainy season has just let up and while you may get a sprinkling here and there the sun usually will peak out again in not time.
Along with the great weather is obviously the great beach, and while Barceloneta will get over crowded no matter the season, there are plenty of the beaten path beaches (like Poblenou) that offer the same great atmosphere, with out the hoards of tourists. Right now is the perfect time to grab your favorite bathing suit and head down to the beach.
Ditching The Lines
Even though the tourists are always going to come in mass, right now is the best time to visit for the simple fact that there just arn't that many tourists in the city yet. Sure walking down Las Ramblas is going to get crowded, in fact most of the major tourist spots should be pretty full, however they won't be overcrowded even Barceloneta will have some space to lounge out (although not much). The cities big draws, will always need to be visited early to ensure getting in at a reasonable time, but you won't ever feel as though you'll need to wake a the crack of dawn to do so.
The nice thing is that even if you do get up a little late, most of the big sites to see won't have lines that are too much to deal with. There are the select few that always tend to get a line around the block (La Segrada Familia, although its better to just see it on the outside) but most other places will usually have lines that a short enough to deal with, even if you did get moving a bit later than you expected.
Life in Technicolor
Barcelona is beautiful during all seasons, even during the gray of Winter and the relentless heat of Summer, but right now id when all the flowers, trees, and plants are springing (no pun intended) back to life in a beautiful boutique of color. The climate is simple perfect for plant life to thrive and you'll no doubt see the brightest greens, deepest blues, and brilliant yellows you could only dream of.
Not only does the season bring out the best in nature it also brings out the best in the people as well. Gone are the slightly chilly days of winter and now that the sun is back the life loving attitude is back as well. People are noticeable more cheery, more outgoing, and in general happier during this time. Once you touch down in Barcelona get ready to make a lot of new friends as everyone is excited to get out and meet new people.