BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
STLBOS

St. Louis, MO (STL) to Boston, MA (BOS) flight delay odds

Historically, 69.3% of scheduled reportable flights on this direction arrived on time in July 2025–June 2026. The sample includes 1,610 flights.

HISTORICAL ROUTE SIGNALVariable
69.3%arrived on time
20.1%30+ min late
1.5%cancelled
1,610scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late10.2%all scheduled flights
120+ minutes late4.0%all scheduled flights
Diverted0.0%did not reach as scheduled
Average arrival+13.6 mincompleted flights

When is this route most reliable?

The same route can behave differently through the day. These are scheduled departure windows, not actual departure times. Small time windows with fewer than 40 flights are withheld.

Departure windowFlightsOn time30+ minCancelled
Early morning20190.0%3.5%1.5%
Late morning42280.3%11.6%0.9%
Afternoon40459.4%28.7%2.0%
Evening57860.9%26.0%1.4%

Weekday comparison

Day-of-week results use at least 30 scheduled flights per row. Look for broad patterns, not tiny percentage differences.

DayFlightsOn time30+ minCancelled
Monday24465.2%23.0%2.5%
Tuesday23575.3%13.2%0.4%
Wednesday22971.6%17.9%0.4%
Thursday23964.9%24.7%0.8%
Friday24075.8%17.5%0.0%
Saturday18069.4%17.8%1.7%
Sunday24363.0%25.5%4.5%

Airline comparison

Marketing-carrier results make codeshare flights easier to compare as travelers buy them. Dedicated route-airline reports require at least 160 flights.

AirlineFlightsOn time30+ minCancelled
Southwest Airlines93465.6%22.1%1.0%
Envoy Air41874.6%18.4%1.7%
Republic Airways25873.6%15.5%3.1%

Monthly trend

Month-by-month results show whether a twelve-month average hides an unusual period.

MonthFlightsOn time30+ minCancelled
July 202514963.8%22.8%2.0%
August 202514584.1%12.4%0.0%
September 202514269.7%20.4%0.7%
October 202515053.3%30.7%0.7%
November 202514075.0%18.6%1.4%
December 202514679.5%13.7%0.7%
January 202610276.5%10.8%5.9%
February 20269877.6%10.2%7.1%
March 202611861.0%24.6%1.7%
April 202613467.9%20.1%0.0%
May 202614264.1%25.4%0.0%
June 202614462.5%25.7%0.7%

What drove reported delay minutes?

BTS cause minutes are reported for qualifying delayed flights. These shares describe recorded delay minutes—not the chance that a particular cause will affect your next flight.

Airline19.7%
Late aircraft46.9%
National airspace28.5%
Weather2.8%
Security2.2%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.