Benchmarked strictly across TripTiming's 5 empirical pillars: Crowds, Weather, Vibes, Prices, and Safety.
While Barcelona captures an advantage on pure Weather (64 vs 62) with 29°C ambient temperatures, Lisbon decisively captures September on Crowds (47 vs 47) and Prices (54 vs 57). Barcelona suffers from seasonal congestion and peak lodging premiums ($291/night), whereas Lisbon delivers a more balanced, friction-free itinerary with approximately $70 in lodging savings on a 7-night stay ($281/night vs $291/night).