Historical on-time performance
St. Louis to Chicago
251 miData through May 2026Source: US DOT · BTS
Flights on STL–MDW arrive on time 80% of the time over the last 12 months.
On-time rate80%arrived within 15 min
p90 delay35 min1 in 10 flights is worse (tail risk)
Cancelled1.1%of scheduled flights
based on 1,706 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- Southwest AirlinesOn-time80%Medianon timep9035 minCancel1.1%Flights1,706
Why flights run late
Delay causes
- Airline25%
- Weather3%
- Air traffic (NAS)19%
- Late aircraft53%
- Security0%
Most delay minutes here are attributed to Late aircraft.
When flights don't go
Why flights were cancelled
- Airline28%
- Weather61%
- Air traffic (NAS)11%
- Security0%
Most cancellations here are attributed to Weather. Shares are among 18 cancellations with a reported cause (BTS reports causes from June 2003).
Over time
On-time trend
By season
On-time rate by month
When to fly
Best time to fly STL → MDW
All airlines · rolling 36 months (2023-06 .. 2026-05).
Best time of day
Mornings are the most reliable time of day to fly this route — 91% on time.
- Mornings91% on time · p90 5 min · 1,748 flights
- Middays85% on time · p90 20 min · 1,161 flights
- Afternoons77% on time · p90 30 min · 918 flights
- Evenings73% on time · p90 40 min · 1,064 flights
- Overnights71% on time · p90 55 min · 755 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 77% to 85% on time.
- Wednesdays85% on time · p90 20 min · 840 flights
- Tuesdays85% on time · p90 25 min · 848 flights
- Saturdays82% on time · p90 30 min · 531 flights
- Fridays81% on time · p90 30 min · 878 flights
- Mondays80% on time · p90 30 min · 873 flights
- Thursdays80% on time · p90 30 min · 869 flights
- Sundays77% on time · p90 35 min · 807 flights
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