Route profile
STL→MDW
Flight reliability, delays and best times to fly from St. Louis to Chicago. · 251 miles
Right now
Current conditions at both ends of this route.
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Airport conditions describe the airfield, not any individual flight. An airport operating normally is not a guarantee that a specific flight will depart on time.
Route reliability
July 2023 – June 2026
Better than 76% of comparable major US routes (4,577 compared)
Calculated from 5,617 flights. How this is calculated
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – June 2026
Best time to fly
On-time arrival rate by scheduled local departure time.
STL → MDW flights departing 5–9 AM arrived on time 92.6% of the time, against 70.4% for 9 PM–5 AM departures — a gap of 22.1 percentage points.
By departure window
By departure hour
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Buckets with fewer than 120 flights are not scored.
Airlines on this route
Performance by the carrier that actually operated the flight.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 5,617 | 82.5% | 1.34% | -7 min | 4.8% |
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Carriers with fewer than 200 flights on this route are not listed.
Other ways to fly St. Louis to Chicago
Airport pairs serving the same journey, grouped by the DOT's own city-market definition. They do not perform the same way.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| STL→ORD St. Louis to Chicago | 8,222 | 75.4% | 1.98% | -5 min | 51 |
| STL→MDW this route St. Louis to Chicago | 5,617 | 82.5% | 1.34% | -7 min | 75 |
STL → MDW is the most reliable pairing for this journey at 82.5% on time, against 75.4% for STL → ORD.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Grouped by DOT city market, which places Newark with the New York airports and Baltimore with the Washington ones.
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Sunday the least, a gap of 8.0 percentage points.
By month
July is historically the weakest month and February the strongest, a spread of 21.6 percentage points.
Historical trend
On-time arrival rate by month.
Over the most recent 12 months (2025-07 to 2026-06), on-time arrivals averaged 79.7% against 85.6% in the 12 months before — declining by 5.9 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026
Data and methodology
All figures on this page are calculated by FlyerIntel from 5,617 STL → MDW flight records published by the US DOT Bureau of Transportation Statistics, covering July 2023 – June 2026. A flight is counted as delayed when it arrives 15 or more minutes after its scheduled arrival time, following BTS methodology. Cancelled and diverted flights have no arrival time and are excluded from on-time rates rather than counted as late.