Seattle (SEA) to San Diego (SAN): 1,051 miles (1,692 km) great-circle, about 2h 35m nonstop by our estimate. Cheapest fare observed: $355 round-trip on Frontier, with 1 stop, departing April 26, 2026.
$355 round-trip, Frontier F94204, departing 2026-04-26 at 21:54, returning 2026-04-28. The recorded itinerary left on a Sunday, returning on a Tuesday 2 nights later; the fare was observed 1 day before departure. "Book this flight" opens Kiwi.com with the same airline and dates.
At $355, it ranked 13th of the 30 round-trip fares we recorded from SEA (median $591). That is 33.8 cents per great-circle mile (round-trip price over one-way distance), above the SEA median of 19.2 cents across 30 round-trip routes.
Routes from SEA of similar length: Denver (1,022 mi) at $242 and Phoenix (1,107 mi) at $279.
Frontier had the cheapest fare on 10 of 30 SEA routes. It is the 25th longest of the 30 routes we track from SEA.
Of 11 departure airports with a fare to San Diego, Seattle (SEA) ranked 10th at $355. Lowest: $76 from San Francisco (SFO); highest: $563 from Washington DC (IAD); 4 nonstop. Cheapest-fare airlines (routes): Frontier (8), Alaska Airlines (2) and WestJet (1).
The reverse, San Diego (SAN) to Seattle (SEA), was $172 round-trip on Frontier, 1 stop, departing June 26, 2026. San Diego to Seattle flights.
Travelpayouts fares (cheapest per route, observed April 25, 2026); OurAirports coordinates and elevations; IANA zones America/Los_Angeles, America/Los_Angeles; flight time is our estimate.