About 1 in 6 DL 4090 flights from Seattle arrived 15+ minutes late, diverted or cancelled over the past year (16%); 0.5% were cancelled. The typical flight landed 8 minutes early.
DL 4090: SEA → BOI
Scheduled to leave Seattle at 9:20 p.m. local time, operated by SkyWest as OO 4090. Over the past year it arrived on time 84% of the time (198 flights), in line with other DL flights on the route at that hour (83%). Last seen in the data Aug 30, 2026.
Usually Delta Air Lines's last flight of the day from Seattle to Boise (93% of days). Delta Air Lines's last SEA–BOI flight was cancelled 0.3% of the time, against 0.2% for its earlier ones. If it's cancelled, the next Delta Air Lines flight is usually around 7:15 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 35 | 91% |
| Tuesday | 27 | 96% |
| Wednesday | 24 | 83% |
| Thursday | 33 | 79% |
| Friday | 35 | 80% |
| Saturday | 9 | — |
| Sunday | 35 | 74% |
Why it was late
All flights SEA → BOI · Connecting off DL 4090? Check the risk
Questions
How often is DL 4090 from SEA to BOI late?
Delta Air Lines 4090 from Seattle, WA to Boise, ID arrived 15 or more minutes late, was diverted or was cancelled on 16% of 198 scheduled flights between September 2025 and August 2026. 0.5% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check Delta Air Lines for today's flight. Method.