Please be aware that Brussels has multiple airports and that these results are for all airports serving the city.
The best month to fly between Brussels and Barcelona is November and the most expensive month to fly is September. (Average prices, based on 332 datapoints.)
The best day to arrive at Brussels is Friday and it would be best to avoid Saturday, as prices are on average 196.6% higher than on Friday. (Average prices, based on 224 datapoints.)
The cheapest airline flying from Brussels to Barcelona is Ryanair. They are 34% cheaper than Brussels Airlines. (Average prices, based on 341 datapoints.)
The best time to fly is at around 15. (Average prices, based on 476 datapoints.)