✈️ Flight Guide: Seattle (SEA) → Lisbon (LIS)

April in Lisbon features notable observances and cultural events that can enhance a trip from Seattle-Tacoma International Airport (SEA). The national holiday on April 25 (Carnation Revolution) includes commemorations, parades, and public gatherings across Lisbon. Easter week brings religious services, local markets, and seasonal culinary offerings in bakeries and restaurants. Spring also ushers in outdoor concerts, weekend markets, and improved conditions for day trips to Sintra and Cascais. Keep local event schedules in mind when booking accommodations and transit, especially around April 25.

April is among the best months to fly from Seattle-Tacoma International Airport (SEA) to Humberto Delgado Airport (LIS) because Lisbon enjoys mild spring weather, fewer tourists than summer, and often lower airfare than peak months. For lowest fares and smaller crowds, fly mid-week (Tuesday–Thursday) and avoid Easter weekend if dates coincide with your travel. Late spring (May) and early fall (September–October) are also excellent for good weather and moderate prices. CTA: Check April and May availability now to plan a spring Lisbon trip from Seattle.

Most travelers from Seattle-Tacoma International Airport (SEA) to Humberto Delgado Airport (LIS) will choose connecting flights in April. Connecting flights often offer lower fares and more schedule flexibility but add layover time. For shorter total travel time, route via a major U.S. East Coast hub (JFK/EWR) or a single efficient European hub (LHR/AMS/CDG). If comfort and fewer transfers are priorities, select airlines with negotiated connections to minimize risk of missed connections. CTA: Compare direct and connecting options for SEA to LIS in April and choose the itinerary that balances cost and convenience.

TAP Air Portugal: Best for competitive transatlantic fares and convenient Lisbon connections when combined with U.S. feeder flights; often competitive pricing in April. Delta/United: Strong U.S. network from SEA to East Coast hubs with reliable scheduling and frequent flyer partnerships; may require separate European partner for final Lisbon leg. British Airways/KLM/Air France: Good European hub options (LHR/AMS/CDG) with comfortable business-class products and predictable single-stop itineraries. For cheapest fares, compare mixed-carrier itineraries that combine a U.S. domestic leg with a European long-haul. Check baggage rules and change fees when comparing total trip cost. CTA: Run an airline comparison for SEA to LIS in April to find the best balance of price, layover, and service.

Pack light layers for April: Lisbon spring temperatures typically range from 12–20°C (54–68°F), so include a light waterproof jacket and comfortable walking shoes. For the SEA departure, expect variable Pacific Northwest weather—bring a compact umbrella and transit-friendly luggage. Allow extra time for connections, monitor airline alerts for weather or holiday-related changes, and purchase travel insurance if your itinerary includes tight connections. Use mobile boarding passes, enroll in TSA PreCheck (SEA), and add a Portuguese SIM or eSIM on arrival for maps and transit apps.

Average total travel time from Seattle-Tacoma International Airport (SEA) to Humberto Delgado Airport (LIS) in April ranges from about 13 to 18 hours including one-stop connections; nonstop air time (if available via seasonal charters) would be roughly 10–11 hours but most passengers will connect. Common connection hubs include New York (JFK/EWR), Boston (BOS), London (LHR), Amsterdam (AMS), and Paris (CDG). For shorter total duration, prioritize late-evening SEA departures that connect efficiently in the East Coast or schedule daytime connections in Europe. Check airline schedules for seasonal adjustments around Easter and the April 25 holiday.

Find the best deals on flights from Seattle-Tacoma International Airport (SEA) to Humberto Delgado Airport (LIS) in April by booking 6–12 weeks in advance and targeting mid-week departures (Tuesdays and Wednesdays). Use flexible-date searches on Google Flights and Skyscanner, set price alerts, and compare multi-airline itineraries—connecting via East Coast hubs (JFK/EWR) or European hubs (LHR/AMS/CDG) often lowers fares. Consider one-stop itineraries if you want significant savings; look for sale periods from legacy carriers and TAP Air Portugal promotions for transatlantic segments. CTA: Start a fare alert for SEA to LIS April flights to lock in the lowest prices.