Historical on-time performance
Boston to Chicago
861 miData through May 2026Source: US DOT · BTS
Flights on BOS–MDW arrive on time 71% of the time over the last 12 months.
On-time rate71%arrived within 15 min
p90 delay55 min1 in 10 flights is worse (tail risk)
Cancelled1.5%of scheduled flights
based on 1,396 flights over the last 12 months. On-time means arriving within 15 minutes (BTS standard).
By airline
How each carrier compares
- Southwest AirlinesOn-time71%Medianon timep9055 minCancel1.5%Flights1,396
Why flights run late
Delay causes
- Airline24%
- Weather2%
- Air traffic (NAS)16%
- Late aircraft58%
- Security0%
Most delay minutes here are attributed to Late aircraft.
When flights don't go
Why flights were cancelled
- Airline10%
- Weather62%
- Air traffic (NAS)29%
- Security0%
Most cancellations here are attributed to Weather. Shares are among 21 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 BOS → 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 10 min · 1,418 flights
- Middays87% on time · p90 15 min · 846 flights
- Afternoons65% on time · p90 65 min · 605 flights
- Overnights53% on time · p90 95 min · 412 flights
- Evenings51% on time · p90 85 min · 770 flights
Best day of week
On-time rates are fairly even by day on this route — ranging from 71% to 81% on time.
- Saturdays81% on time · p90 30 min · 519 flights
- Wednesdays80% on time · p90 35 min · 532 flights
- Tuesdays78% on time · p90 40 min · 537 flights
- Mondays74% on time · p90 60 min · 609 flights
- Fridays72% on time · p90 55 min · 621 flights
- Thursdays71% on time · p90 60 min · 617 flights
- Sundays71% on time · p90 60 min · 616 flights
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