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 July. (Average prices, based on 620 datapoints.)
The best day to arrive at Brussels is Monday and it would be best to avoid Tuesday, as prices are on average 30.11% higher than on Monday. (Average prices, based on 620 datapoints.)
The cheapest airline flying from Brussels to Lisbon is Ryanair. They are 56% cheaper than Brussels Airlines. (Average prices, based on 626 datapoints.)
The best time to fly is at around 11. (Average prices, based on 745 datapoints.)