August is the cheapest month to fly this route, with average fares around $229 round trip.
Average round-trip fares by departure month, based on current availability.
| Month | Avg Price | Lowest | Relative Cost | |
|---|---|---|---|---|
| May 2026 | $290 | $240 | Peak | |
| June 2026 | $279 | $230 | ||
| July 2026 | $251 | $210 | ||
| August 2026 | $229 | $210 | Best |
Departing on Tuesday offers the lowest average fares at $247. Sunday departures are the most expensive at $284, a difference of $37.
The best time to fly is August. Set up an alert and we'll notify you when prices drop.
Get Started Free →The cheapest month to fly from Chicago to Seattle is August, with average round-trip fares around $229. The lowest fare found in August is $210.
Tuesday departures are the cheapest, averaging $247 round trip. The most expensive day is Sunday at $284.
Based on current pricing trends, booking for August travel offers the best value. Avoid May if possible, as fares average $290 compared to $229 in the cheapest month. June is a solid middle-ground option at $279.
Flying in August instead of May can save you approximately $61 per round trip. The cheapest month averages $229 while the most expensive averages $290.
Airlines, flight times, price calendar, and more for Chicago to Seattle
View ORD → SEA Details