69% of flights from Chicago to San Diego arrived on time over the past 12 months. That is worse than the typical U.S. route. The 7 a.m. departures ran on time 89% of the time; the 9 p.m. ones 41%. Most reliable airline: United Airlines (76%). 11% 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 ORD → SAN: when a flight was late, it was under 45 minutes late 56% of the time. About 1 in 10 flights landed an hour or more late, and 1 in 58 three hours or more; 1.3% were cancelled outright.
- On time or early69%
- 15–30 min late10%
- 30–60 min late9.1%
- 1–2 hours late6.1%
- 2–3 hours late1.9%
- 3+ hours late1.7%
- Diverted0.3%
- Cancelled1.3%
Share of all 3,945 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 |
|---|---|---|---|---|---|---|---|
| United Airlines | 1,677 | 76% | 0.4% | −4 min | 6.7% | +62 min | United Airlines |
| American Airlines | 1,400 | 63% | 1.6% | +2 min | 12.9% | +64 min | American Airlines |
| Alaska Airlines | 862 | 67% | 2.5% | −3 min | 10.6% | +73 min | Alaska Airlines |
| Frontier Airlines | 6 | — | — | — | — | — | Frontier 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 ORD). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | United Airlines | American Airlines | Alaska Airlines |
|---|---|---|---|
| 6 a.m. | — | 85% | — |
| 7 a.m. | 91% | — | — |
| 8 a.m. | 83% | — | 74% |
| 9 a.m. | — | 64% | — |
| 10 a.m. | — | 68% | — |
| 11 a.m. | — | 67% | — |
| 1 p.m. | 79% | — | — |
| 2 p.m. | — | — | 61% |
| 3 p.m. | — | — | 71% |
| 4 p.m. | 62% | — | — |
| 5 p.m. | — | 66% | — |
| 6 p.m. | — | 62% | — |
| 7 p.m. | 59% | 50% | 52% |
| 8 p.m. | 69% | — | — |
| 9 p.m. | — | 41% | — |
Last flight of the day
On ORD → SAN, each airline's last flight of the day was cancelled 2.7% of the time, against 0.8% for its earlier flights (3.6× as often). It arrived 3+ hours late 2.1% of the time (earlier flights: 1.6%). 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 |
|---|---|---|---|---|---|
| American Airlines | 9:17 p.m. | 3.3% | 1.7% | 1.0% | first flight 6:45 a.m. |
| Alaska Airlines | 7:59 p.m. | 4.2% | 3.3% | 1.5% | first flight 6:20 a.m. |
| United Airlines | 8:05 p.m. | 0.8% | 1.4% | 0.3% | first flight 7:01 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 SAN tonight, book an earlier flight so there's a backup if it's cancelled.
By month
Each calendar month pooled over 2023–2026. Best: October (79%). Worst: August (66%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 596 | 65% | 1.7% |
| Tuesday | 546 | 77% | 0.5% |
| Wednesday | 539 | 72% | 0.7% |
| Thursday | 579 | 66% | 0.9% |
| Friday | 583 | 63% | 0.7% |
| Saturday | 514 | 78% | 1.6% |
| Sunday | 588 | 66% | 2.9% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 27 · airline 13 · air traffic/airport 11
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| UA 2428 | 7:00 a.m. | 180 | 93% | 0.6% | −14 min | United Airlines |
| AS 1470 | 8:20 a.m. | 309 | 75% | 1.3% | −8 min | Alaska Airlines |
| UA 660 | 8:46 a.m. | 365 | 82% | 0.0% | −11 min | United Airlines |
| AA 2131 | 10:05 a.m. | 235 | 67% | 1.3% | 0 min | American Airlines |
| UA 2683 | 1:00 p.m. | 311 | 78% | 0.3% | −7 min | United Airlines |
| AS 1447 | 2:20 p.m. | 293 | 67% | 1.7% | −4 min | Alaska Airlines |
| UA 745 | 4:05 p.m. | 156 | 65% | 1.3% | +2 min | United Airlines |
| AA 1543 | 5:49 p.m. | 237 | 63% | 3.4% | +3 min | American Airlines |
| AS 1466 | 7:59 p.m. | 187 | 49% | 5.3% | +11 min | Alaska Airlines |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Nov 29, 2025 | 10 | 0% | 4 |
| Jan 25, 2026 | 8 | 0% | 1 |
| Dec 7, 2025 | 10 | 10% | 2 |
| Sep 13, 2025 | 9 | 11% | 0 |
| Aug 31, 2026 | 13 | 15% | 2 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of Chicago or San Diego. None has been clearly more reliable than ORD → SAN.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| ORD → SAN (this route) | 3,945 | 69% | 1.3% |
| MDW → SAN Chicago Midway to San Diego | 1,110 | 68% | 1.2% |
Questions
How often are flights from ORD to SAN on time?
69% of 3,945 scheduled flights from Chicago, IL to San Diego, CA arrived within 15 minutes of schedule between September 2025 and August 2026. 1.3% were cancelled.
What is the best time of day to fly ORD to SAN?
Flights scheduled to leave at 7 a.m. were the most reliable (89% on time). The 9 p.m. departures were the least (41%).
Which airline is most on time from ORD to SAN?
United Airlines: 76% of its 1,677 flights on the route arrived on time. American Airlines: 63%. Alaska Airlines: 67%.
What month has the most delays from ORD to SAN?
August (66% on time). The best month is October (79%), over 2023–2026.
Is the last flight of the day from ORD to SAN more likely to be cancelled?
Yes. Each airline's last ORD–SAN flight of the day was cancelled 2.7% of the time over the past year, against 0.8% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- SAN → ORD (return)
- Chicago O'Hare (ORD) delays by hour
- Flights into San Diego (SAN)
- United Airlines on-time record
- American Airlines on-time record
- Alaska Airlines on-time record
- Frontier 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.