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

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

85.2% of 2,551 official scheduled ONT-to-SEA flights arrived on time; 7.7% 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
85.2%arrived on time
7.7%30+ min late
1.3%cancelled
2,551scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late3.5%all scheduled flights
120+ minutes late1.5%all scheduled flights
Diverted0.1%did not reach as scheduled
Average arrival-1.2 mincompleted flights

Which departure time was most reliable for ONT to SEA?

Among qualifying ONT-to-SEA departure window results, Early morning had the highest on-time rate: 93.0% of 744 flights. Evening was lowest at 77.0% across 530 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning74493.0%3.4%0.4%
Late morning52890.7%4.9%1.5%
Afternoon74079.2%9.5%2.6%
Evening53077.0%14.2%0.6%

Which weekday was most reliable for ONT to SEA?

Among qualifying ONT-to-SEA weekday results, Tuesday had the highest on-time rate: 87.6% of 356 flights. Friday was lowest at 81.2% across 383 flights.

DayFlightsOn time30+ minCancelled
Monday38785.0%7.8%1.0%
Tuesday35687.6%5.9%0.0%
Wednesday34087.4%7.6%0.6%
Thursday37183.3%9.7%1.1%
Friday38381.2%9.4%3.4%
Saturday32486.7%6.8%1.2%
Sunday39085.6%6.4%1.5%

Which airline was most reliable for ONT to SEA?

Among qualifying ONT-to-SEA airline results, SkyWest Airlines had the highest on-time rate: 91.7% of 1,085 flights. Alaska Airlines was lowest at 79.7% across 1,268 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines1,26879.7%10.3%2.4%
SkyWest Airlines1,08591.7%4.2%0.3%
Frontier Airlines16982.8%11.2%0.0%
Delta Air Lines2993.1%3.4%0.0%

Which month was most reliable for ONT to SEA?

Among qualifying ONT-to-SEA month results, February 2026 had the highest on-time rate: 95.6% of 135 flights. July 2025 was lowest at 79.1% across 302 flights.

MonthFlightsOn time30+ minCancelled
July 202530279.1%10.6%3.0%
August 202526683.1%10.2%0.8%
September 202521387.3%3.8%0.5%
October 202520084.0%8.5%1.0%
November 202521184.4%8.1%3.3%
December 202520080.5%12.0%1.0%
January 202615887.3%7.6%0.6%
February 202613595.6%3.0%0.0%
March 202617785.9%8.5%1.7%
April 202620090.5%4.0%0.5%
May 202624988.4%6.8%0.8%
June 202624083.3%6.2%1.2%

What drove ONT to SEA delay minutes?

Airline was the largest recorded ONT-to-SEA delay category, accounting for 41.6% of 21,663 BTS-attributed delay minutes during July 2025–June 2026.

Airline41.6%
Late aircraft37.3%
National airspace15.7%
Weather5.3%
Security0.0%
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.