BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
SEA→ONT

Seattle, WA (SEA) to Ontario, CA (ONT) flight delay odds

81.9% of 2,550 official scheduled SEA-to-ONT flights arrived on time; 9.5% arrived at least 30 minutes late and 1.3% were cancelled during July 2025–June 2026.

Source: U.S. Bureau of Transportation Statistics · Reporting window: July 2025–June 2026 · Updated September 16, 2026

HISTORICAL ROUTE SIGNALLower disruption
81.9%arrived on time
9.5%30+ min late
1.3%cancelled
2,550scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late4.1%all scheduled flights
120+ minutes late1.4%all scheduled flights
Diverted0.0%did not reach as scheduled
Average arrival+0.9 mincompleted flights

Which departure time was most reliable for SEA to ONT?

Among qualifying SEA-to-ONT departure window results, Early morning had the highest on-time rate: 88.5% of 616 flights. Night was lowest at 66.4% across 220 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning61688.5%5.0%2.9%
Late morning36983.5%8.4%1.4%
Afternoon83178.0%11.8%0.7%
Evening51485.8%7.6%0.2%
Night22066.4%20.0%0.9%

Which weekday was most reliable for SEA to ONT?

Among qualifying SEA-to-ONT weekday results, Saturday had the highest on-time rate: 85.5% of 324 flights. Friday was lowest at 76.8% across 383 flights.

DayFlightsOn time30+ minCancelled
Monday38882.7%9.0%1.3%
Tuesday35684.3%8.1%0.0%
Wednesday33982.9%9.4%0.3%
Thursday37180.1%11.3%1.1%
Friday38376.8%11.0%3.1%
Saturday32485.5%8.0%1.5%
Sunday38981.7%9.5%1.3%

Which airline was most reliable for SEA to ONT?

Among qualifying SEA-to-ONT airline results, SkyWest Airlines had the highest on-time rate: 89.4% of 1,084 flights. Alaska Airlines was lowest at 75.8% across 1,268 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines1,26875.8%12.2%2.1%
SkyWest Airlines1,08489.4%5.9%0.4%
Frontier Airlines16977.5%13.6%1.2%
Delta Air Lines2993.1%3.4%0.0%

Which month was most reliable for SEA to ONT?

Among qualifying SEA-to-ONT month results, September 2025 had the highest on-time rate: 91.1% of 213 flights. July 2025 was lowest at 69.9% across 302 flights.

MonthFlightsOn time30+ minCancelled
July 202530269.9%17.9%3.3%
August 202526677.4%11.3%0.4%
September 202521391.1%5.2%0.0%
October 202520087.0%9.5%1.0%
November 202521180.1%7.1%3.3%
December 202520071.5%15.0%1.0%
January 202615784.7%7.0%0.6%
February 202613584.4%8.1%0.0%
March 202617784.7%7.9%1.7%
April 202620089.5%5.0%0.0%
May 202624985.5%7.2%0.8%
June 202624084.2%8.3%1.7%

What drove SEA to ONT delay minutes?

Airline was the largest recorded SEA-to-ONT delay category, accounting for 48.3% of 21,659 BTS-attributed delay minutes during July 2025–June 2026.

Airline48.3%
Late aircraft31.4%
National airspace12.6%
Weather7.2%
Security0.4%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.