autumnThere is a really good chance of rain in Barcelona from September to November. Although spring can bring rain too, precipitation is definitely at its highest in autumn and winter. In September, when the weather is still hot, there are thunderstorms.
How many days for Barcelona is enough?
Barcelona is easily worth two days, and no one would regret having a third day (or a fourth, or a fifth…). If you can spare only one full day for the city, it will be a scramble, but a day you'll never forget.