Seattle to Bellingham

What the Data Says About SEA to BLI

The Seattle to Bellingham corridor (SEA → BLI) covers roughly 93 miles and is served by 2 carriers, based on Bureau of Transportation Statistics reporting. Across 5,958 flights in the dataset, this route posts a 85.1% on-time rate with an average delay of 51.4 minutes when flights run late. Over the most recent 24 months of BTS data, 2,325 flights were recorded on this pairing — 32 cancelled (1.4%) and 0 diverted (0.0%). Those baseline metrics tell you what to expect before you book.

Having 2 carriers on the route matters: more carriers generally means more daily schedule options, competitive pricing, and redundancy when flights are cancelled. With 5,958 total flights analyzed, the 85.1% on-time figure is statistically meaningful rather than a small-sample fluke. The 51.4-minute average delay applies only to flights that actually ran late, so it is not the average wait across all departures — the majority of flights on this route depart on time under the BTS definition of a delay (15+ minutes past schedule).

Looking at recent months, Dec 2024 posted the best performance on this corridor at 94% on-time, while Jun 2025 came in at 71% on-time — a 23-point gap between best and worst recent month. For travelers evaluating the SEA to BLI route, the combination of a 85.1% on-time rate, 51.4-minute average delay, 1.4% recent cancellation rate, and 2 available carriers is the concrete summary of what BTS data shows about reliability on this pairing.