SFO to ONT flight delays & on-time performance
Nonstop flights from San Francisco International Airport to Ontario International Airport · 363 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at SFO or ONT right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from San Francisco (SFO) to Ontario (ONT) arrived on time 76% of the time in Aug 2025 – Jul 2026, worse than the 78% national average.
- 0.9% were cancelled, and 7% arrived an hour or more late.
- United Airlines was the most punctual airline here (81% on time); Frontier Airlines was the least (56%).
- Departures scheduled around 8am did best (86% on time); around 10pm did worst (44%).
- Tuesday was the most reliable day to fly (81% on time) and Friday the least (73%).
- The largest source of delay minutes was late-arriving aircraft (55%).
Which airline is most on time from SFO to ONT?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| United Airlines | 81% | 0.3% | 11 min | 4.5% | 982 |
| SkyWest AirlinesRegional airline operating flights for United Express, Delta Connection, American Eagle and Alaska. | 68% | 2.3% | 24 min | 10.1% | 132 |
| Frontier Airlines | 56% | 3.1% | 42 min | 18.4% | 196 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 8am86%83 flights
- 9am76%84 flights
- 10am82%251 flights
- 11am64%73 flights
- 4pm81%355 flights
- 6pm79%14 flights
- 7pm100%38 flights
- 9pm74%310 flights
- 10pm44%89 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday74%0.5% cancelled
- Tuesday81%0.0% cancelled
- Wednesday77%0.0% cancelled
- Thursday74%1.6% cancelled
- Friday73%0.9% cancelled
- Saturday81%0.6% cancelled
- Sunday77%2.4% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Late-arriving aircraft55%
- Airline (crew, maintenance, cleaning, fueling)28%
- Air traffic control & airport congestion14%
- Extreme weather3%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Airline (crew, maintenance, cleaning, fueling)42%
- Extreme weather33%
- Air traffic control & airport congestion25%
- Security0%
SFO to ONT: common questions
- How often are SFO to ONT flights on time?
- 76% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from San Francisco to Ontario cancelled?
- 0.9% of scheduled flights were cancelled (12 of 1,310).
- How long are typical delays?
- Across all flights the average arrival delay was 17 min (early arrivals count as zero). Flights that were late arrived 66 min behind schedule on average, and 7.1% of flights were an hour or more late.
- How long is taxi time at SFO?
- Flights on this route spent 22 min taxiing from the gate to takeoff on average.
Related routes
Return trip: ONT to SFO — 62% on time
More flights from San Francisco
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: SFO → ONT, nonstop flights by US airlines that report to the DOT. How we calculate this.