Airport month record
ONTJAN
Ontario International in January 2026
- Departures
- 1,892
- Month
- January 2026
- National, same month
- 79.2%
- Carriers
- 7
Historical statistics for January 2026, not live status or a forecast for this year’s January. For today’s conditions at ONT, see live FAA status.
ONT in January earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 79.2%. When something does go wrong the average delay runs an hour and a half. That rests on 1,892 flights, with a median arrival 10 minutes early.
Set against the rest of the country, ONT's January record is 7 points better than the US average of 79.2%. That gap is worth roughly 73 fewer late arrivals for every thousand flights.
Key figures
On time
86.5%
Arrivals under 15 minutes late, of 1,859 completed departures
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
1.69%
Nationally in January: 4.71%
Whole year
81.9%
ONT across all twelve months
These figures cover 1,892 departures from Ontario International in January 2026. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.
Against the year
January next to ONT's other months
Against ONT's own year, January ran 5 points better than the twelve-month rate of 81.9%, which makes it number two of twelve months, best first. Cancellations are where January stands out: 1.69% of scheduled departures were called off, 1.9 times the airport's rate across the year. Either side of it, December ran 82.4% on time and February 87.8%, so this month sits in line with its neighbours.
| Month | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| September 2025 | 2,177 | 84.8% | 76 min | 0.51% | B+ |
| October 2025 | 2,265 | 81.6% | 64 min | 0.49% | B+ |
| November 2025 | 2,184 | 81.9% | 63 min | 2.06% | B |
| December 2025 | 2,132 | 82.4% | 70 min | 0.70% | B+ |
| January 2026 (this page) | 1,892 | 86.5% | 87 min | 1.69% | A |
| February 2026 | 1,734 | 87.8% | 70 min | 0.35% | A+ |
| March 2026 | 2,081 | 82.8% | 57 min | 1.01% | B |
| April 2026 | 2,119 | 82.8% | 61 min | 0.28% | B+ |
| May 2026 | 2,298 | 80.0% | 58 min | 0.70% | B+ |
| June 2026 | 2,304 | 76.7% | 66 min | 1.00% | B |
| July 2026 | 2,377 | 77.9% | 75 min | 0.88% | B+ |
| August 2026 | 2,228 | 80.9% | 70 min | 0.81% | B+ |
Departure window
The best time of day to leave ONT in January
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 1,892 flights.
- 5am–8am552 flights91.5%
- 8am–11am278 flights88.5%
- 11am–2pm366 flights83.0%
- 2pm–5pm341 flights83.3%
- 5pm–8pm231 flights82.5%
- 8pm–5am124 flights86.6%
Scale runs 75% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.5% of the time, against 82.5% for the evening window. That is 9 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 552 flights scheduled in it.
Across the week, Tuesday is the strongest day at 92.4% on time and Friday the weakest at 84.4%, a spread of 8 points.
Carrier by carrier
Which airlines ran best at ONT in January
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 876 | 87.9% | 44 min | 0.57% | A+ |
| American Airlinesthin sample | 292 | 82.9% | 92 min | 5.48% | B− |
| Alaska Airlinesthin sample | 178 | 89.3% | 86 min | 0.56% | A+ |
| United Airlinesthin sample | 167 | 89.2% | 169 min | 0.60% | A+ |
| Delta Air Linesthin sample | 146 | 82.9% | 127 min | 4.11% | B− |
| Frontier Airlinesthin sample | 144 | 83.0% | 115 min | 2.08% | B |
| SkyWest Airlinesthin sample | 89 | 84.3% | 183 min | 0.00% | B+ |
Route by route
Busiest routes out of ONT in January
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| ONT to PHX · Phoenixthin sample | 261 | 85.3% | 57 min | 0.77% | A+ |
| ONT to LAS · Las Vegasthin sample | 213 | 85.3% | 73 min | 0.94% | A+ |
| ONT to DEN · Denverthin sample | 185 | 88.0% | 63 min | 0.54% | A+ |
| ONT to DFW · Dallas-Fort Worththin sample | 168 | 82.2% | 135 min | 8.93% | B− |
| ONT to SEA · Seattlethin sample | 158 | 87.9% | 128 min | 0.63% | A+ |
| ONT to SMF · Sacramentothin sample | 155 | 87.1% | 51 min | 0.00% | A+ |
| ONT to OAK · Oaklandthin sample | 120 | 90.7% | 48 min | 1.67% | A |
| ONT to SJC · San Josethin sample | 101 | 94.1% | 36 min | 0.00% | A+ |
| ONT to SFO · San Franciscothin sample | 93 | 82.6% | 175 min | 1.08% | B |
| ONT to SLC · Salt Lake Citythin sample | 92 | 86.7% | 62 min | 2.17% | A |
| ONT to ATL · Atlantathin sample | 65 | 77.0% | 177 min | 6.15% | B− |
| ONT to PDX · Portlandthin sample | 61 | 91.8% | 109 min | 0.00% | A+ |
| ONT to IAH · Houstonthin sample | 41 | 87.8% | 123 min | 0.00% | A+ |
| ONT to DAL · Dallasthin sample | 34 | 81.8% | 48 min | 2.94% | B |
| ONT to HNL · Honoluluthin sample | 31 | 93.5% | 124 min | 0.00% | A+ |
| ONT to HOU · Houstonthin sample | 31 | 87.1% | 29 min | 0.00% | A+ |
Delay causes
What held ONT up in January
Carrier accounts for 42% of the 22,000 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Carrier
- 39%Late-arriving aircraft
- 14%National Airspace System
- 4%Extreme weather
- 0%Security
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 22,000 reported delay minutes here, that single category outweighs weather by 10 to one. The split is drawn from 21,943 reported delay minutes.
Cancellations sit at 1.69% against a national 4.71%, which is ordinary. Diversions add another 0.05%.
Badly late arrivals are rare here: only 4.7% land an hour or more behind schedule, against 7.6% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
What to do with this
Flying from ONT in January
For a January trip through ONT: this is one of the better months to be flying from here, 86.5% on time with 1.69% cancelled. That is a base rate for the month as a whole; a single storm can still spoil a particular day.
Related
Where to go next
- Ontario International (ONT), the whole year
- ONT in September84.8%
- ONT in October81.6%
- ONT in November81.9%
- ONT in December82.4%
- ONT in February87.8%
- ONT in March82.8%
- ONT in April82.8%
- ONT in May80.0%
- ONT in June76.7%
- ONT in July77.9%
- ONT in August80.9%
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.