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 Lisbon is January and the most expensive month to fly is November. (Average prices, based on 387 datapoints.)
The best day to arrive at Brussels is Wednesday and it would be best to avoid Friday, as prices are on average 35.31% higher than on Wednesday. (Average prices, based on 404 datapoints.)
The cheapest airline flying from Brussels to Lisbon is Ryanair. They are 49% cheaper than TAP Portugal. (Average prices, based on 395 datapoints.)