A 4 to 5-night trip to Lisbon in August 2026 for 2 adults from London costs $895–$1,172 in verified flight+stay combinations, based on 5 real date options Valora priced against live supplier data, verified as of Jun 29, 2026. The best-value option departs Aug 16 and returns Aug 20, on TAP Portugal, staying at Charming Guesthouse - Sónias Houses, for $895 total — flight, stay and estimated transfers for those exact dates and 2 adults, never a per-night rate scaled up. The full Edit below compares every option and adds the weather, sea temperature, crowds and local knowledge for those dates, with a source link on every claim.