43% of flights from Chicago to San Francisco arrived on time over the past 12 months. That is worse than the typical U.S. route. The 9 p.m. departures ran on time 39% of the time; the 10 a.m. ones 26%. 18% 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 MDW → SFO: when a flight was late, it was under 45 minutes late 52% of the time. About 1 in 6 flights landed an hour or more late, and 1 in 86 three hours or more; 1.2% were cancelled outright.
- On time or early43%
- 15–30 min late18%
- 30–60 min late21%
- 1–2 hours late12%
- 2–3 hours late3.9%
- 3+ hours late1.2%
- Diverted0.2%
- Cancelled1.2%
Share of all 516 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 | 516 | 43% | 1.2% | +20 min | 16.9% | +55 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 MDW). Delays build through the day as late planes knock on, so early flights usually do best.
Last flight of the day
On MDW → SFO, each airline's last flight of the day was cancelled 2.2% of the time, against 0.6% for its earlier flights (4.0× as often). It arrived 3+ hours late 1.7% of the time (earlier flights: 1.7%). 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. | 2.2% | 1.7% | 0.6% | first flight 10:05 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.
If you need to be in SFO tonight, book an earlier flight so there's a backup if it's cancelled.
By month
Each calendar month pooled over 2023–2026. Best: September (75%). Worst: April (34%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 76 | — | — |
| Tuesday | 69 | — | — |
| Wednesday | 68 | — | — |
| Thursday | 75 | — | — |
| Friday | 75 | — | — |
| Saturday | 77 | — | — |
| Sunday | 76 | — | — |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 5 · air traffic/airport 1
Month by month
Not enough months with data to draw a trend.
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of Chicago or San Francisco. ORD → SFO has been 23 points more reliable.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| MDW → SFO (this route) | 516 | 43% | 1.2% |
| ORD → SFO Chicago O'Hare to San Francisco | 5,649 | 65% | 1.1% |
| MDW → SJC Chicago Midway to San Jose | 526 | 64% | 1.3% |
| MDW → OAK Chicago Midway to Oakland | 525 | 60% | 1.3% |
Questions
How often are flights from MDW to SFO on time?
43% of 516 scheduled flights from Chicago, IL to San Francisco, CA 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 MDW to SFO?
Flights scheduled to leave at 9 p.m. were the most reliable (39% on time). The 10 a.m. departures were the least (26%).
What month has the most delays from MDW to SFO?
April (34% on time). The best month is September (75%), over 2023–2026.
Is the last flight of the day from MDW to SFO more likely to be cancelled?
Yes. Each airline's last MDW–SFO flight of the day was cancelled 2.2% of the time over the past year, against 0.6% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- SFO → MDW (return)
- Chicago Midway (MDW) delays by hour
- Flights into San Francisco (SFO)
- 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.