78% of flights from St. Louis to Chicago arrived on time over the past 12 months. That is about the typical U.S. route. The 5 a.m. departures ran on time 90% of the time; the 4 p.m. ones 59%. 7% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for STL → MDW: when a flight was late, it was under 45 minutes late 65% of the time. About 1 in 19 flights landed an hour or more late, and 1 in 154 three hours or more; 1.2% were cancelled outright.
- On time or early78%
- 15–30 min late8.7%
- 30–60 min late6.3%
- 1–2 hours late3.4%
- 2–3 hours late1.2%
- 3+ hours late0.6%
- Diverted0.2%
- Cancelled1.2%
Share of all 1,698 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| Southwest Airlines | 1,698 | 78% | 1.2% | −6 min | 5.2% | +52 min | Southwest Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at STL). Delays build through the day as late planes knock on, so early flights usually do best.
Last flight of the day
On STL → MDW, each airline's last flight of the day was cancelled 0.5% of the time, against 1.4% for its earlier flights, so here the last flight is actually the safer one. It arrived 3+ hours late 0.5% of the time (earlier flights: 0.7%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| Southwest Airlines | 9:30 p.m. | 0.5% | 0.5% | 1.4% | first flight 5:40 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
By month
Each calendar month pooled over 2023–2026. Best: February (91%). Worst: July (70%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 268 | 74% | 1.9% |
| Tuesday | 260 | 87% | 0.4% |
| Wednesday | 255 | 80% | 0.8% |
| Thursday | 254 | 76% | 0.8% |
| Friday | 259 | 77% | 1.9% |
| Saturday | 165 | 78% | 1.2% |
| Sunday | 237 | 77% | 1.3% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 12 · airline 6 · air traffic/airport 2
Month by month
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Mar 16, 2026 | 5 | 0% | 0 |
| Jan 26, 2026 | 4 | 0% | 1 |
| Nov 29, 2025 | 4 | 0% | 2 |
| Jun 11, 2026 | 6 | 17% | 0 |
| Jul 1, 2026 | 6 | 17% | 0 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of St. Louis or Chicago. None has been clearly more reliable than STL → MDW.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| STL → MDW (this route) | 1,698 | 78% | 1.2% |
| STL → ORD St. Louis Lambert to Chicago O'Hare | 5,247 | 69% | 3.2% |
Questions
How often are flights from STL to MDW on time?
78% of 1,698 scheduled flights from St. Louis, MO to Chicago, IL arrived within 15 minutes of schedule between September 2025 and August 2026. 1.2% were cancelled.
What is the best time of day to fly STL to MDW?
Flights scheduled to leave at 5 a.m. were the most reliable (90% on time). The 4 p.m. departures were the least (59%).
What month has the most delays from STL to MDW?
July (70% on time). The best month is February (91%), over 2023–2026.
Is the last flight of the day from STL to MDW more likely to be cancelled?
No, the opposite. Each airline's last STL–MDW flight of the day was cancelled 0.5% of the time over the past year, against 1.4% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- MDW → STL (return)
- St. Louis Lambert (STL) delays by hour
- Flights into Chicago Midway (MDW)
- Southwest Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.