Route profile
BOS→MDW
Flight reliability, delays and best times to fly from Boston to Chicago, 861 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 34% of comparable major US routes (4,598 compared)
Calculated from 4,229 flights. How this is calculated
BOS → MDW arrives on time 75.4% of the time; the return trip, MDW → BOS, arrives on time 71.5% of the time, a 3.9-point gap between the two directions of the same city pair.
BOS → MDW spends 21.2 minutes on the ground on an 861-mile trip: 16.0 minutes from pushback to wheels-up at BOS and 5.2 minutes from touchdown to gate at MDW.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
On-time performance swings unusually widely by time of day here, wider than 100% of 4,023 comparable routes.
93.2% on time for 9 AM–12 PM departures, against 50.2% for 6–9 PM.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,023 in the comparison.
What sets this route apart
Where BOS to MDW differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
BOS to MDW struggles most at 8 PM: 43.5% of its flights scheduled then arrive on time, 23 points behind the 66.5% on routes of similar length at the same hour. Against all other routes the gap is 23.9 points.
BOS to MDW is at its best against routes of similar length for flights scheduled at 10 AM: 94.3% arrive on time, 11.1 points ahead of the 83.2% those routes manage at that hour. Against all other routes the gap is 11.6 points.
Thursday is the day BOS to MDW slips furthest against routes of similar length, 71.7% on time where they average 76.5%, 4.8 points lower. Against all other routes the gap is 5.1 points.
In September, BOS to MDW runs 10.6 points below routes of similar length, 71.8% on time to 82.4%. Against all other routes the gap is 10.6 points.
BOS to MDW against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 8 PM departures | 43.5% | routes of similar length | 66.5% | −23.0 pts | 200 here, 138,966 there |
| Hour: 10 AM departures | 94.3% | routes of similar length | 83.2% | +11.1 pts | 227 here, 159,999 there |
| Weekday: Thursday | 71.7% | routes of similar length | 76.5% | −4.8 pts | 630 here, 401,619 there |
| Month: September | 71.8% | routes of similar length | 82.4% | −10.6 pts | 390 here, 212,622 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 861 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
Why BOS → MDW flights are cancelled
July 2023 – July 2026
BOS → MDW cancelled 55 of 4,229 scheduled flights — about 1 in every 77. The reason filed most often was extreme weather, 69.1% of the cancellations coded on this route — about 1 in every 111 scheduled flights.
Share of cancellations
Of 55 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
38 cancellations, 69.1% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
13 cancellations, 23.6% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
4 cancellations, 7.3% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. With only one or two carriers on the route, the split mostly reflects how they file. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
55 coded cancellations were recorded on BOS → MDW; the section appears from 50.
When it goes wrong
July 2023 – July 2026
54 min late
against a median of 4 min early
Percentiles over 4,229 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at MDW after arriving from BOS.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 40% | Likely to miss |
| 45 min | 24% | High risk |
| 60 min | 16% | High risk |
| 90 min | 8.4% | Some risk |
| 120 min | 4.9% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.30% of the time and diverts 0.38% of the time, which a late arrival never shows up in.
Chance of missing is the share of 4,158 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 54 minutes late (90th-percentile gate arrival delay), over 4,229 operations.
Any other layover length: connection checker.
Best time to fly
BOS → MDW flights departing 9 AM–12 PM arrived on time 93.2% of the time, against 50.2% for 6–9 PM departures, a gap of 43.0 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 92.7% on time from 419 flights
- 6 AM: 92.6% on time from 331 flights
- 7 AM: 92.6% on time from 411 flights
- 8 AM: 85.5% on time from 175 flights
- 9 AM: 93.8% on time from 161 flights
- 10 AM: 94.3% on time from 228 flights
- 11 AM: too few flights to score
- 12 PM: 85.2% on time from 309 flights
- 1 PM: 77.2% on time from 225 flights
- 2 PM: 76.9% on time from 200 flights
- 3 PM: 65.1% on time from 238 flights
- 4 PM: 52.7% on time from 203 flights
- 5 PM: 50.3% on time from 365 flights
- 6 PM: 51.8% on time from 288 flights
- 7 PM: 55.3% on time from 173 flights
- 8 PM: 43.5% on time from 208 flights
- 9 PM: 70.8% on time from 170 flights
- 10 PM to 11 PM: too few flights to score
Why BOS → MDW runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for BOS → MDW. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on BOS → MDW, at 60.0%: flights here mostly leave late because the plane came in late, and the day shows it: 9 AM–12 PM departures arrived on time 93.2% of the time and 6–9 PM departures 50.2%.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 4,229 | 75.4% | 1.30% | -4 min | 8.6% |
Other ways to fly Boston to Chicago
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| BOS→ORD Boston to Chicago | 21,884 | 76.9% | 2.02% | -7 min | 54 |
| BOS→MDW this route Boston to Chicago | 4,229 | 75.4% | 1.30% | -4 min | 60 |
BOS → MDW is the most reliable pairing for this journey at 75.4% on time, against 76.9% for BOS → ORD.
Weekly and seasonal patterns
By day of week
Saturday is historically the most reliable day and Sunday the least, a gap of 10.4 percentage points.
By month
- Jan: 81.4%
- Feb: 82.3%
- Mar: 81.6%
- Apr: 82.1%
- May: 70.1%
- Jun: 68.7%
- Jul: 67.5%
- Aug: 75.1%
- Sep: 71.8%
- Oct: 78.1%
- Nov: 87.2%
- Dec: 77.4%
July is historically the weakest month and November the strongest, a spread of 19.7 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 63.4% from 137 flights
- August 2023: 65.6% from 132 flights
- September 2023: 67.2% from 130 flights
- October 2023: 78.2% from 142 flights
- November 2023: too few flights to score (101)
- December 2023: too few flights to score (100)
- January 2024: too few flights to score (83)
- February 2024: too few flights to score (75)
- March 2024: too few flights to score (97)
- April 2024: too few flights to score (105)
- May 2024: too few flights to score (111)
- June 2024: 67.3% from 161 flights
- July 2024: 70.7% from 170 flights
- August 2024: 78.7% from 144 flights
- September 2024: 89.7% from 136 flights
- October 2024: 85.0% from 140 flights
- November 2024: too few flights to score (89)
- December 2024: too few flights to score (91)
- January 2025: too few flights to score (71)
- February 2025: too few flights to score (66)
- March 2025: too few flights to score (67)
- April 2025: too few flights to score (90)
- May 2025: too few flights to score (101)
- June 2025: 68.8% from 157 flights
- July 2025: 71.2% from 172 flights
- August 2025: 80.5% from 135 flights
- September 2025: 57.1% from 128 flights
- October 2025: 71.0% from 139 flights
- November 2025: too few flights to score (88)
- December 2025: too few flights to score (90)
- January 2026: too few flights to score (69)
- February 2026: too few flights to score (63)
- March 2026: too few flights to score (113)
- April 2026: too few flights to score (119)
- May 2026: 73.8% from 123 flights
- June 2026: 70.3% from 143 flights
- July 2026: 63.3% from 151 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 72.3% against 79.2% in the 12 months before — declining by 6.9 percentage points.
Data and methodology
Calculated by FlyerIntel from 4,229 BOS → MDW flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed