Sunny Barcelona is a tourist destination year-round for good reason -- the Mediterranean climate is fairly mild for most of the year.
August is the one month you should try to avoid, because it gets so hot and humid that even the locals leave. August is the month when Barcelona is a sticky tourist town with few restaurants and stores open.
If you want to hit the beach, try May, June, or September. The weather will be warm but not sizzling, and the temperature of the water will be just right for swimming.
Winters are cold, but rarely freezing, and there’s never much snow or ice.
January and February are usually pretty sunny and see fewer tourists, making it a great time to enjoy the city’s atmosphere.
Though Barcelona is known for its pleasant weather, there’s still a good chance of rain any time of the year, so always pack an umbrella just in case.
You’ll also want to book in advance no matter when you’re going, because Barcelona is always popular.
But as long as you come prepared and avoid visiting when Barcelona is at its hottest and most touristy, the best time to visit depends on what you want to get out of your stay.