76% of flights from Boston to Baltimore arrived on time over the past 12 months. That is worse than the typical U.S. route. The 7 a.m. departures ran on time 94% of the time; the 8 p.m. ones 46%. Most reliable airline: Delta Air Lines (78%). 11% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for BOS → BWI: when a flight was late, it was under 45 minutes late 51% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 71 three hours or more; 2.9% were cancelled outright.
- On time or early76%
- 15–30 min late7.0%
- 30–60 min late6.4%
- 1–2 hours late4.7%
- 2–3 hours late1.4%
- 3+ hours late1.4%
- Diverted0.3%
- Cancelled2.9%
Share of all 3,536 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| Southwest Airlines | 2,413 | 75% | 2.3% | −7 min | 7.9% | +67 min | Southwest Airlines |
| Delta Air Lines | 1,099 | 78% | 4.3% | −11 min | 6.5% | +68 min | Republic Airways |
| Spirit Airlines | 24 | — | — | — | — | — | Spirit Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at BOS). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | Southwest Airlines | Delta Air Lines |
|---|---|---|
| 5 a.m. | 93% | — |
| 6 a.m. | — | 93% |
| 7 a.m. | 93% | — |
| 8 a.m. | 88% | 86% |
| 9 a.m. | 92% | — |
| noon | 85% | — |
| 1 p.m. | 81% | 82% |
| 2 p.m. | 75% | — |
| 3 p.m. | 67% | 72% |
| 4 p.m. | 55% | — |
| 5 p.m. | 59% | 72% |
| 6 p.m. | 48% | — |
| 7 p.m. | 48% | — |
| 8 p.m. | 41% | — |
Last flight of the day
On BOS → BWI, each airline's last flight of the day was cancelled 5.0% of the time, against 2.4% for its earlier flights (2.1× as often). It arrived 3+ hours late 2.1% of the time (earlier flights: 1.2%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| Delta Air Lines | 8:35 p.m. | 6.3% | 2.0% | 3.4% | first flight 6:35 a.m. |
| Southwest Airlines | 9:00 p.m. | 3.8% | 2.2% | 2.1% | first flight 5:45 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
If you need to be in BWI tonight, book an earlier flight so there's a backup if it's cancelled.
By month
Each calendar month pooled over 2023–2026. Best: November (86%). Worst: July (67%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 544 | 70% | 4.8% |
| Tuesday | 504 | 80% | 4.0% |
| Wednesday | 497 | 82% | 0.8% |
| Thursday | 529 | 75% | 1.7% |
| Friday | 536 | 77% | 1.9% |
| Saturday | 407 | 80% | 2.0% |
| Sunday | 519 | 66% | 5.0% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 47 · air traffic/airport 38 · airline 18
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| DL 5703 | 6:35 a.m. | 249 | 88% | 2.8% | −15 min | Republic Airways |
| DL 5668 | 11:10 a.m. | 194 | 81% | 3.6% | −10 min | Republic Airways |
| DL 5644 | 5:25 p.m. | 331 | 72% | 6.0% | −8 min | Republic Airways |
| DL 5851 | 8:35 p.m. | 133 | 55% | 7.5% | −1 min | Republic Airways |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Dec 14, 2025 | 10 | 0% | 1 |
| Jan 25, 2026 | 9 | 0% | 9 |
| Feb 22, 2026 | 9 | 0% | 7 |
| Feb 23, 2026 | 9 | 0% | 9 |
| Jun 23, 2026 | 10 | 10% | 0 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of Boston or Baltimore. MHT → BWI has been 12 points more reliable.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| BOS → BWI (this route) | 3,536 | 76% | 2.9% |
| MHT → BWI Manchester-Boston to Baltimore/Washington | 1,721 | 88% | 0.8% |
| PVD → BWI Rhode Island T. F. Green to Baltimore/Washington | 1,850 | 85% | 1.9% |
| BOS → IAD Boston Logan to Washington Dulles | 1,527 | 81% | 3.0% |
| PVD → IAD Rhode Island T. F. Green to Washington Dulles | 1,157 | 78% | 2.5% |
| MHT → IAD Manchester-Boston to Washington Dulles | 731 | 75% | 3.6% |
| BOS → DCA Boston Logan to Washington Reagan National | 9,105 | 69% | 4.1% |
Questions
How often are flights from BOS to BWI on time?
76% of 3,536 scheduled flights from Boston, MA to Baltimore, MD arrived within 15 minutes of schedule between September 2025 and August 2026. 2.9% were cancelled.
What is the best time of day to fly BOS to BWI?
Flights scheduled to leave at 7 a.m. were the most reliable (94% on time). The 8 p.m. departures were the least (46%).
Which airline is most on time from BOS to BWI?
Delta Air Lines: 78% of its 1,099 flights on the route arrived on time. Southwest Airlines: 75%.
What month has the most delays from BOS to BWI?
July (67% on time). The best month is November (86%), over 2023–2026.
Is the last flight of the day from BOS to BWI more likely to be cancelled?
Yes. Each airline's last BOS–BWI flight of the day was cancelled 5.0% of the time over the past year, against 2.4% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- BWI → BOS (return)
- Boston Logan (BOS) delays by hour
- Flights into Baltimore/Washington (BWI)
- Southwest Airlines on-time record
- Delta Air Lines on-time record
- Spirit Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.