SEA (Seattle) to BOS (Boston) flights arrive on time 77% of the time. The most reliable airline on this route is Southwest Airlines at 80%. The average delay is 37 minutes. Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Source: Bureau of Transportation Statistics. Updated March 2026.SEA → BOS
SEA (Seattle) to BOS (Boston)
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SEA → BOS on-time performance by month
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This route is on time most of the time. About 77% of flights arrive on schedule.
Delays on this route are most often caused by the airline (crew, maintenance, or boarding).
Airlines are roughly equal on this route — Southwest Airlines leads slightly at 80% vs JetBlue Airways at 76%.
Airline Comparison
Southwest Airlines leads at 80% on time; JetBlue Airways trails at 76%.
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Data last updated March 2026. Source: Bureau of Transportation Statistics.