Southwest Airlines STL to BOS on-time performance
Southwest Airlines nonstop flights from St. Louis to Boston · Aug 2025 – Jul 2026
On-time arrivals
66%
arrived < 15 min late
Cancelled
0.7%
7 flights
Avg arrival delay
22 min
60 min when late
Rank on route
#3 of 3
route average 70% on time
Key facts
- Southwest Airlines flights on STL to BOS arrived on time 66% of the time in Aug 2025 – Jul 2026.
- 0.7% were cancelled, and 12% arrived an hour or more late.
- That ranks #3 of 3 airlines on this route, which averaged 70% on time overall.
- The largest source of delay minutes was late-arriving aircraft (43%).
On-time trend by month
Why this airline's flights were late
- Late-arriving aircraft43%
- Air traffic control & airport congestion32%
- Airline (crew, maintenance, cleaning, fueling)22%
- Extreme weather3%
- Security1%
Other airlines on STL to BOS
- Envoy Air76% on time · 19 min avg delay
- Republic Airways74% on time · 25 min avg delay
Full STL to BOS comparison →
Southwest Airlines on-time record across all routes →
934 Southwest Airlines flights tracked on this route; 7 cancelled, 2 diverted.
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. How we calculate this.