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Route on-time record

SFO to ONT: most on-time flights and the best time to fly

San Francisco (San Francisco International Airport) to Ontario (Ontario International Airport). 1,275 nonstop flights in Jun 2025 to May 2026, 77% arrived within 15 minutes and 0.9% were cancelled. The most reliable flight number was United 1503 at 8:25 AM.

Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.

SFO → ONT

San Francisco to Ontario: 1,275 nonstop flights a year

On time (12 months)

77%

Cancelled

0.9%

avg delay 18 min

Best time to leave

6 to 9 PM

95% on time vs 65% after 9 PM

Most reliable airline

United

80% chance on time

Check SFO to ONT fares

Lowest nonstop fare seen in the next two months: $31 (Frontier 1160 on 2026-10-26). Fares open on our travel partner (Aviasales). Pick the flight number you chose here.

Most reliable nonstop flights

Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.

  1. #1 · United 1503

    8:25 AM → 9:56 AM1h 31m nonstop

    Local times, typical schedule. Last flown 2026-04-28.

    86%

    chance on time

    On time (history)
    92%
    Cancelled
    0.0%
    Avg arrival delay
    14 min
    • Arrived on time 92% of the time (24 flights, Jun 2025 to May 2026).
    • Departs inside SFO's trouble window: 61% of its 333 ground stops and delay programs started between 7 AM and 1 PM.
    • Short track record (24 flights), so its score leans on the airline's record at this hour.

    Limited track record · 24 flights

    Find United 1503 fares Opens this date on Aviasales

  2. #2 · United 1316

    8:10 AM → 9:41 AM1h 31m nonstop

    Local times, typical schedule. Last flown 2026-05-20.

    86%

    chance on time

    On time (history)
    90%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 90% of the time (21 flights, Jun 2025 to May 2026).
    • Departs inside SFO's trouble window: 61% of its 333 ground stops and delay programs started between 7 AM and 1 PM.
    • Short track record (21 flights), so its score leans on the airline's record at this hour.

    Limited track record · 21 flights

    Find United 1316 fares Opens this date on Aviasales

  3. #3 · United 1561

    4:10 PM → 5:47 PM1h 37m nonstop

    Local times, typical schedule. Last flown 2026-05-20.

    86%

    chance on time

    On time (history)
    89%
    Cancelled
    0.0%
    Avg arrival delay
    6 min
    • Arrived on time 89% of the time (76 flights, Jun 2025 to May 2026).
    • Never cancelled in 76 scheduled flights.
    • Departs outside SFO's trouble window (7 AM to 1 PM, when 61% of its 333 ground stops and delay programs started).

    Moderate track record · 76 flights

    Find United 1561 fares Opens this date on Aviasales

  4. #4 · United 552

    9:09 PM → 10:45 PM1h 36m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    82%

    chance on time

    On time (history)
    86%
    Cancelled
    0.8%
    Avg arrival delay
    8 min
    • Arrived on time 86% of the time (132 flights, Jun 2025 to May 2026).
    • Leaves in this route's least on-time window (After 9 PM: 65% on time; 6 to 9 PM: 95%).
    • Departs outside SFO's trouble window (7 AM to 1 PM, when 61% of its 333 ground stops and delay programs started).

    Moderate track record · 132 flights

    Find United 552 fares Opens this date on Aviasales

  5. #5 · United 2661

    10:50 AM → 12:20 PM1h 30m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    74%

    chance on time

    On time (history)
    74%
    Cancelled
    0.0%
    Avg arrival delay
    13 min
    • Arrived on time 74% of the time (103 flights, Jun 2025 to May 2026).
    • Never cancelled in 103 scheduled flights.
    • Departs inside SFO's trouble window: 61% of its 333 ground stops and delay programs started between 7 AM and 1 PM.

    Moderate track record · 103 flights

    Find United 2661 fares Opens this date on Aviasales

  6. #6 · SkyWest 5613 · sold as United Express, Delta Connection, American Eagle or Alaska

    4:17 PM → 5:56 PM1h 39m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    64%

    chance on time

    On time (history)
    50%
    Cancelled
    11.1%
    Avg arrival delay
    50 min
    • Arrived on time 50% of the time (24 flights, Jun 2025 to May 2026).
    • Departs outside SFO's trouble window (7 AM to 1 PM, when 61% of its 333 ground stops and delay programs started).
    • 63% of its delay minutes came from the plane arriving late from an earlier flight.
    • Short track record (24 flights), so its score leans on the airline's record at this hour.

    Limited track record · 24 flights

    Find 4:17 PM flight fares Opens this date on Aviasales

  7. #7 · Frontier 2678

    9:19 AM → 10:51 AM1h 32m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    56%

    chance on time

    On time (history)
    54%
    Cancelled
    3.1%
    Avg arrival delay
    50 min
    • Arrived on time 54% of the time (156 flights, Jun 2025 to May 2026).
    • Cancelled 3.1% of the time (5 of 161).
    • Departs inside SFO's trouble window: 61% of its 333 ground stops and delay programs started between 7 AM and 1 PM.
    • 62% of its delay minutes came from the plane arriving late from an earlier flight.

    Moderate track record · 156 flights

    Find Frontier 2678 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • United Airlines80%

    1,037 flights · 81% on time as flown · 0.4% cancel

  • SkyWest Airlines (sold as United Express, Delta Connection, American Eagle or Alaska)70%

    77 flights · 68% on time as flown · 1.9% cancel

  • Frontier Airlines60%

    161 flights · 54% on time as flown · 2.0% cancel

On time by departure time

All airlines, scheduled local departure, Jun 2025 to May 2026.

  • Before 9 AM86%

    83 flights · avg delay 11 min

  • 9 AM to noon82%

    347 flights · avg delay 8 min

  • 3 to 6 PM82%

    362 flights · avg delay 15 min

  • 6 to 9 PM95%

    55 flights · avg delay 6 min

  • After 9 PM65%

    428 flights · avg delay 31 min

Best day: Wednesday (86%). Worst: Monday (77%).

Smarter routing

Nearby airports that run more on time

  • SJC → LAX 87% chance on time

    Norman Y. Mineta San Jose International Airport to Los Angeles International Airport · 4,405 flights a year · 77 mi from your airports · yours: 76%

    Rank flightsFares

  • SJC → SNA 87% chance on time

    Norman Y. Mineta San Jose International Airport to John Wayne Orange County International Airport · 2,679 flights a year · 60 mi from your airports · yours: 76%

    Rank flightsFares

  • OAK → LGB 86% chance on time

    Oakland San Francisco Bay Airport to Long Beach International Airport · 1,649 flights a year · 47 mi from your airports · yours: 76%

    Rank flightsFares

  • OAK → SNA 86% chance on time

    Oakland San Francisco Bay Airport to John Wayne Orange County International Airport · 2,387 flights a year · 41 mi from your airports · yours: 76%

    Rank flightsFares

On time by month

All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.

J
85
F
81
M
82
A
84
M
81
J
76
J
79
A
82
S
83
O
86
N
76
D
76

What delays this route

  • Late-arriving aircraft55%
  • Airline (crew, maintenance, boarding)30%
  • Air traffic control and airport volume13%
  • Severe weather3%

Share of delay minutes by the cause airlines report to the US DOT.

Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure

SFO to ONT questions

What time of day is best to fly SFO to ONT?
6 to 9 PM: 95% of flights arrived on time, against 65% for departures after 9 PM.
Which airline is most on time from SFO to ONT?
United, with a season-adjusted 80% chance of operating and arriving on time over 1,037 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
What is the worst month for delays on SFO to ONT?
November (76% on time); the best was October (86%), averaged over Jun 2023 to May 2026.
Is this a prediction for my flight?
No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.

More routes from SFO

Live status: FAA delays and ground stops