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

Ontario, CA (ONT) to Denver, CO (DEN) flight delay odds

79.1% of 2,672 official scheduled ONT-to-DEN flights arrived on time; 12.9% arrived at least 30 minutes late and 0.4% 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 SIGNALGenerally reliable
79.1%arrived on time
12.9%30+ min late
0.4%cancelled
2,672scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late7.4%all scheduled flights
120+ minutes late2.4%all scheduled flights
Diverted0.3%did not reach as scheduled
Average arrival+7.0 mincompleted flights

Which departure time was most reliable for ONT to DEN?

Among qualifying ONT-to-DEN departure window results, Early morning had the highest on-time rate: 91.3% of 1,121 flights. Afternoon was lowest at 67.0% across 941 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning1,12191.3%3.8%0.4%
Late morning27381.7%8.8%0.4%
Afternoon94167.0%21.1%0.3%
Evening23567.7%24.7%0.9%
Night10276.5%20.6%1.0%

Which weekday was most reliable for ONT to DEN?

Among qualifying ONT-to-DEN weekday results, Saturday had the highest on-time rate: 82.9% of 334 flights. Thursday was lowest at 77.5% across 409 flights.

DayFlightsOn time30+ minCancelled
Monday40577.5%14.8%0.0%
Tuesday35778.7%11.5%0.3%
Wednesday35578.3%13.8%0.0%
Thursday40977.5%14.9%0.5%
Friday40778.4%13.3%1.0%
Saturday33482.9%10.8%0.3%
Sunday40580.7%10.9%1.0%

Which airline was most reliable for ONT to DEN?

Among qualifying ONT-to-DEN airline results, United Airlines had the highest on-time rate: 84.4% of 853 flights. Southwest Airlines was lowest at 75.3% across 1,267 flights.

AirlineFlightsOn time30+ minCancelled
Southwest Airlines1,26775.3%14.0%0.4%
United Airlines85384.4%10.0%0.4%
Frontier Airlines55279.5%14.9%0.7%

Which month was most reliable for ONT to DEN?

Among qualifying ONT-to-DEN month results, January 2026 had the highest on-time rate: 87.6% of 185 flights. July 2025 was lowest at 64.0% across 272 flights.

MonthFlightsOn time30+ minCancelled
July 202527264.0%26.1%1.1%
August 202525472.8%19.3%0.4%
September 202523781.0%13.5%0.0%
October 202524185.5%7.9%0.8%
November 202522083.6%8.6%0.0%
December 202519576.9%15.4%0.0%
January 202618587.6%6.5%0.5%
February 202617185.4%7.0%1.2%
March 202620071.5%12.5%1.5%
April 202620585.9%7.3%0.0%
May 202624283.9%9.5%0.0%
June 202625076.8%15.2%0.0%

What drove ONT to DEN delay minutes?

Late aircraft was the largest recorded ONT-to-DEN delay category, accounting for 42.5% of 37,392 BTS-attributed delay minutes during July 2025–June 2026.

Airline21.7%
Late aircraft42.5%
National airspace34.1%
Weather1.4%
Security0.3%
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.