Route on-time record
SJC to ONT: most on-time flights and the best time to fly
San Jose (Norman Y. Mineta San Jose International Airport) to Ontario (Ontario International Airport). 1,317 nonstop flights in Jun 2025 to May 2026, 84% arrived within 15 minutes and 0.0% were cancelled. The most reliable flight number was Southwest 4132 at 6:30 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
SJC → ONT
San Jose to Ontario: 1,317 nonstop flights a year
On time (12 months)
84%
Cancelled
0.0%
avg delay 8 min
Best time to leave
Before 9 AM
98% on time vs 44% after 9 PM
Most reliable airline
Southwest
84% chance on time
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 · Southwest 4132
6:30 AM → 7:50 AM1h 20m nonstop
Local times, typical schedule. Last flown 2026-04-06.
94%
chance on time
- On time (history)
- 97%
- Cancelled
- 0.0%
- Avg arrival delay
- 1 min
- Arrived on time 97% of the time (33 flights, Jun 2025 to May 2026).
- Never cancelled in 33 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 98% on time; After 9 PM: 44%).
- Short track record (33 flights), so its score leans on the airline's record at this hour.
Limited track record · 33 flights
Find Southwest 4132 fares Opens this date on Aviasales#2 · Southwest 4253
7:10 AM → 8:25 AM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31.
92%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 3 min
- Arrived on time 93% of the time (55 flights, Jun 2025 to May 2026).
- Never cancelled in 55 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 98% on time; After 9 PM: 44%).
- Short track record (55 flights), so its score leans on the airline's record at this hour.
Limited track record · 55 flights
Find Southwest 4253 fares Opens this date on Aviasales#3 · Southwest 1173
10:40 AM → 12:00 PM1h 20m nonstop
Local times, typical schedule. Last flown 2026-05-30.
92%
chance on time
- On time (history)
- 96%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 96% of the time (47 flights, Jun 2025 to May 2026).
- Never cancelled in 47 scheduled flights.
- Short track record (47 flights), so its score leans on the airline's record at this hour.
Limited track record · 47 flights
Find Southwest 1173 fares Opens this date on Aviasales#4 · Southwest 4138
11:05 AM → 12:25 PM1h 20m nonstop
Local times, typical schedule. Last flown 2026-04-06.
88%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 3 min
- Arrived on time 93% of the time (28 flights, Jun 2025 to May 2026).
- Short track record (28 flights), so its score leans on the airline's record at this hour.
Limited track record · 28 flights
Find Southwest 4138 fares Opens this date on Aviasales#5 · Southwest 3303
9:50 AM → 11:05 AM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31.
83%
chance on time
- On time (history)
- 75%
- Cancelled
- 0.0%
- Avg arrival delay
- 10 min
- Arrived on time 75% of the time (8 flights, Jun 2025 to May 2026).
- Short track record (8 flights), so its score leans on the airline's record at this hour.
Limited track record · 8 flights
Find Southwest 3303 fares Opens this date on Aviasales#6 · Southwest 4255
4:50 PM → 6:10 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31.
81%
chance on time
- On time (history)
- 80%
- Cancelled
- 0.0%
- Avg arrival delay
- 11 min
- Arrived on time 80% of the time (55 flights, Jun 2025 to May 2026).
- Never cancelled in 55 scheduled flights.
- 73% of its delay minutes came from the plane arriving late from an earlier flight.
- Short track record (55 flights), so its score leans on the airline's record at this hour.
Limited track record · 55 flights
Find Southwest 4255 fares Opens this date on Aviasales#7 · Southwest 948
5:00 PM → 6:15 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-04-06.
78%
chance on time
- On time (history)
- 87%
- Cancelled
- 0.0%
- Avg arrival delay
- 12 min
- Arrived on time 87% of the time (15 flights, Jun 2025 to May 2026).
- Short track record (15 flights), so its score leans on the airline's record at this hour.
Limited track record · 15 flights
Find Southwest 948 fares Opens this date on Aviasales#8 · Southwest 3166
8:00 PM → 9:15 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-04-06.
76%
chance on time
- On time (history)
- 79%
- Cancelled
- 0.0%
- Avg arrival delay
- 9 min
- Arrived on time 79% of the time (33 flights, Jun 2025 to May 2026).
- Never cancelled in 33 scheduled flights.
- Short track record (33 flights), so its score leans on the airline's record at this hour.
Limited track record · 33 flights
Find Southwest 3166 fares Opens this date on Aviasales#9 · Southwest 1522
8:20 PM → 9:35 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31.
69%
chance on time
- On time (history)
- 59%
- Cancelled
- 0.0%
- Avg arrival delay
- 20 min
- Arrived on time 59% of the time (27 flights, Jun 2025 to May 2026).
- 76% of its delay minutes came from the plane arriving late from an earlier flight.
- Short track record (27 flights), so its score leans on the airline's record at this hour.
Limited track record · 27 flights
Find Southwest 1522 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Southwest Airlines84%
1,317 flights · 84% on time as flown · 0.0% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM98%
363 flights · avg delay 1 min
- 9 AM to noon87%
268 flights · avg delay 7 min
- Noon to 3 PM89%
126 flights · avg delay 5 min
- 3 to 6 PM74%
235 flights · avg delay 14 min
- 6 to 9 PM77%
276 flights · avg delay 13 min
- After 9 PM44%
49 flights · avg delay 25 min
Best day: Wednesday (90%). Worst: Sunday (79%).
Smarter routing
Nearby airports that run more on time
MRY → LAX 87% chance on time
Monterey Regional Airport to Los Angeles International Airport · 852 flights a year · 101 mi from your airports · yours: 84%
SJC → LAX 87% chance on time
Norman Y. Mineta San Jose International Airport to Los Angeles International Airport · 4,405 flights a year · 47 mi from your airports · yours: 84%
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 · 30 mi from your airports · yours: 84%
OAK → LGB 86% chance on time
Oakland San Francisco Bay Airport to Long Beach International Airport · 1,649 flights a year · 65 mi from your airports · yours: 84%
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.
What delays this route
- Late-arriving aircraft67%
- Airline (crew, maintenance, boarding)29%
- Air traffic control and airport volume4%
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
SJC to ONT questions
- What time of day is best to fly SJC to ONT?
- Before 9 AM: 98% of flights arrived on time, against 44% for departures after 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from SJC to ONT?
- Southwest, with a season-adjusted 84% chance of operating and arriving on time over 1,317 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 SJC to ONT?
- July (80% on time); the best was November (91%), 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 SJC
- ONT to SJC (return)
- SJC to SAN 74%
- SJC to LAX 87%
- SJC to SEA 83%
- SJC to LAS 80%
- SJC to PHX 83%
- SJC to SNA 87%
- SJC to DEN 81%
- SJC to BUR 84%
- SJC to SLC 92%
- SJC to PDX 85%
- SJC to LGB 86%
- SJC to DFW 81%
Live status: FAA delays and ground stops