Airport month record
ONTMAR
Ontario International in March 2026
- Departures
- 2,081
- Month
- March 2026
- National, same month
- 75.7%
- Carriers
- 7
Historical statistics for March 2026, not live status or a forecast for this year’s March. For today’s conditions at ONT, see live FAA status.
ONT in March lands a B, 7 points better than the national rate of 75.7%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 2,081 flights, with a median arrival 8 minutes early.
Set against the rest of the country, ONT's March record is 7 points better than the US average of 75.7%. That gap is worth roughly 71 fewer late arrivals for every thousand flights.
Key figures
On time
82.8%
Arrivals under 15 minutes late, of 2,054 completed departures
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
1.01%
Nationally in March: 2.90%
Whole year
81.9%
ONT across all twelve months
These figures cover 2,081 departures from Ontario International in March 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
March next to ONT's other months
Against ONT's own year, March ran level with the twelve-month rate of 81.9%, which makes it number four of twelve months, best first. Either side of it, February ran 87.8% on time and April 82.8%, so a trip moved by a few weeks would have landed in a better stretch.
| 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 | 1,892 | 86.5% | 87 min | 1.69% | A |
| February 2026 | 1,734 | 87.8% | 70 min | 0.35% | A+ |
| March 2026 (this page) | 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 March
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 points, against half a point between the best and worst carrier.
- 5am–8am567 flights90.9%
- 8am–11am268 flights81.3%
- 11am–2pm354 flights82.2%
- 2pm–5pm311 flights72.7%
- 5pm–8pm284 flights82.0%
- 8pm–5am297 flights80.5%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.9% of the time, against 72.7% for the afternoon window. That is 18 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 567 flights scheduled in it.
Across the week, Tuesday is the strongest day at 87.8% on time and Saturday the weakest at 74.5%, a spread of 13 points.
Carrier by carrier
Which airlines ran best at ONT in March
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 | 984 | 81.8% | 49 min | 0.20% | B+ |
| American Airlinesthin sample | 335 | 85.8% | 52 min | 0.90% | A+ |
| United Airlinesthin sample | 214 | 85.1% | 72 min | 2.34% | A |
| Alaska Airlinesthin sample | 160 | 81.0% | 59 min | 1.25% | B |
| Frontier Airlinesthin sample | 131 | 70.5% | 69 min | 1.53% | C |
| Delta Air Linesthin sample | 130 | 87.6% | 45 min | 4.62% | A− |
| SkyWest Airlinesthin sample | 127 | 88.9% | 107 min | 0.79% | A+ |
Route by route
Busiest routes out of ONT in March
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| ONT to PHX · Phoenixthin sample | 289 | 85.4% | 52 min | 0.35% | A+ |
| ONT to DEN · Denverthin sample | 200 | 73.0% | 47 min | 1.50% | C |
| ONT to LAS · Las Vegasthin sample | 197 | 79.2% | 59 min | 0.00% | B+ |
| ONT to DFW · Dallas-Fort Worththin sample | 184 | 81.7% | 53 min | 1.09% | B |
| ONT to SMF · Sacramentothin sample | 183 | 88.0% | 59 min | 0.00% | A+ |
| ONT to SEA · Seattlethin sample | 177 | 87.4% | 75 min | 1.69% | A |
| ONT to OAK · Oaklandthin sample | 121 | 96.7% | 64 min | 0.00% | A+ |
| ONT to SJC · San Josethin sample | 107 | 83.2% | 76 min | 0.00% | B+ |
| ONT to SFO · San Franciscothin sample | 103 | 91.1% | 45 min | 1.94% | A |
| ONT to SLC · Salt Lake Citythin sample | 94 | 87.8% | 55 min | 4.26% | A− |
| ONT to ATL · Atlantathin sample | 62 | 86.0% | 40 min | 3.23% | A− |
| ONT to IAH · Houstonthin sample | 40 | 78.9% | 96 min | 5.00% | B− |
| ONT to PDX · Portlandthin sample | 38 | 86.8% | 88 min | 0.00% | A+ |
| ONT to AUS · Austinthin sample | 32 | 71.9% | 25 min | 0.00% | C+ |
| ONT to DAL · Dallasthin sample | 31 | 64.5% | 39 min | 0.00% | D+ |
| ONT to HNL · Honoluluthin sample | 31 | 64.5% | 58 min | 0.00% | D+ |
| ONT to HOU · Houstonthin sample | 31 | 25.8% | 47 min | 0.00% | F+ |
| ONT to MDW · Chicagothin sample | 31 | 93.5% | 73 min | 0.00% | A+ |
| ONT to CLT · Charlottethin sample | 31 | 86.7% | 31 min | 3.23% | A− |
Delay causes
What held ONT up in March
Late-arriving aircraft accounts for 46% of the 20,000 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Late-arriving aircraft
- 28%Carrier
- 23%National Airspace System
- 3%Extreme weather
- 0%Security
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 20,000 reported delay minutes here, that single category outweighs weather by 16 to one. The split is drawn from 19,985 reported delay minutes.
Cancellations sit at 1.01% against a national 2.90%, which is ordinary. Diversions add another 0.29%.
5.1% of arrivals land an hour or more late, close to the national 9.5%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
What to do with this
Flying from ONT in March
For a March trip through ONT: expect 82.8% on time and 1.01% cancelled, going by March 2026. The 5am–8am window was the strongest part of the 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 January86.5%
- ONT in February87.8%
- 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.