ONT to SFO flight delays & on-time performance
Nonstop flights from Ontario International Airport to San Francisco International Airport · 363 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at ONT or SFO right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Ontario (ONT) to San Francisco (SFO) arrived on time 62% of the time in Aug 2025 – Jul 2026, worse than the 78% national average.
- 0.8% were cancelled, and 13% arrived an hour or more late.
- United Airlines was the most punctual airline here (69% on time); Frontier Airlines was the least (39%).
- Departures scheduled around 6am did best (91% on time); around 8pm did worst (14%).
- Saturday was the most reliable day to fly (72% on time) and Monday the least (55%).
- The largest source of delay minutes was air traffic control & airport congestion (59%).
Which airline is most on time from ONT to SFO?
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 | 69% | 0.4% | 21 min | 9.5% | 981 |
| SkyWest AirlinesRegional airline operating flights for United Express, Delta Connection, American Eagle and Alaska. | 42% | 1.5% | 37 min | 20.8% | 132 |
| Frontier Airlines | 39% | 2.6% | 43 min | 25.1% | 196 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 6am91%327 flights
- 8am24%47 flights
- 9am51%45 flights
- 10am47%38 flights
- 11am32%28 flights
- 1pm69%341 flights
- 6pm46%327 flights
- 8pm14%49 flights
- 9pm64%45 flights
- 10pm57%51 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday55%1.0% cancelled
- Tuesday70%0.6% cancelled
- Wednesday58%0.0% cancelled
- Thursday60%1.5% cancelled
- Friday62%0.5% cancelled
- Saturday72%0.6% cancelled
- Sunday61%1.4% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Air traffic control & airport congestion59%
- Late-arriving aircraft24%
- Airline (crew, maintenance, cleaning, fueling)15%
- Extreme weather3%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Airline (crew, maintenance, cleaning, fueling)45%
- Extreme weather36%
- Air traffic control & airport congestion18%
- Security0%
ONT to SFO: common questions
- How often are ONT to SFO flights on time?
- 62% 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 Ontario to San Francisco cancelled?
- 0.8% of scheduled flights were cancelled (11 of 1,309).
- How long are typical delays?
- Across all flights the average arrival delay was 26 min (early arrivals count as zero). Flights that were late arrived 65 min behind schedule on average, and 12.9% of flights were an hour or more late.
- How long is taxi time at ONT?
- Flights on this route spent 24 min taxiing from the gate to takeoff on average.
Related routes
Return trip: SFO to ONT — 76% on time
More flights from Ontario
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: ONT → SFO, nonstop flights by US airlines that report to the DOT. How we calculate this.