Skip to content

All Products

Aviation Intelligence

Alerts & Airspace

Free Pilot Tools & Widgets

RC Aviation

Games & Learning

Weather Research & More

Pilot Resources

My Airports

Your shortcuts, saved on this device. Search to add an airport.

No airports saved yet. Add the fields you visit most.

Ask ATIS

Route on-time record

IAH to ONT: most on-time flights and the best time to fly

Houston (George Bush Intercontinental Airport) to Ontario (Ontario International Airport). 517 nonstop flights in Jun 2025 to May 2026, 73% arrived within 15 minutes and 0.4% were cancelled. The most reliable flight number was United 1563 at 8:14 PM.

Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.

IAH → ONT

Houston to Ontario: 517 nonstop flights a year

On time (12 months)

73%

Cancelled

0.4%

avg delay 18 min

Best time to leave

Noon to 3 PM

74% on time vs 60% 3 to 6 PM

Most reliable airline

United

75% chance on time

Check IAH to ONT fares

Lowest nonstop fare seen in the next two months: $111 (United 1563 on 2026-11-10). Fares open on our travel partner (Aviasales). Pick the flight number you chose here.

Most reliable nonstop flights

Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.

  1. #1 · United 1563

    8:14 PM → 9:50 PM3h 36m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    74%

    chance on time

    On time (history)
    74%
    Cancelled
    0.3%
    Avg arrival delay
    20 min
    • Arrived on time 74% of the time (321 flights, Jun 2025 to May 2026).
    • Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
    • 58% of its delay minutes came from the plane arriving late from an earlier flight.

    Strong track record · 321 flights

    Find United 1563 fares Opens this date on Aviasales

  2. #2 · Frontier 3131

    6:00 AM → 7:35 AM3h 37m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    69%

    chance on time

    On time (history)
    70%
    Cancelled
    0.7%
    Avg arrival delay
    16 min
    • Arrived on time 70% of the time (151 flights, Jun 2025 to May 2026).
    • Departs outside IAH's trouble window (noon to 6 PM, when 60% of its 92 ground stops and delay programs started).
    • 59% of its delay minutes came from the plane arriving late from an earlier flight.

    Moderate track record · 151 flights

    Find Frontier 3131 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • United Airlines75%

    365 flights · 75% on time as flown · 0.3% cancel

  • Frontier Airlines70%

    152 flights · 70% on time as flown · 0.5% cancel

On time by departure time

All airlines, scheduled local departure, Jun 2025 to May 2026.

  • Noon to 3 PM74%

    31 flights · avg delay 13 min

  • 3 to 6 PM60%

    81 flights · avg delay 21 min

  • 6 to 9 PM74%

    366 flights · avg delay 20 min

Best day: Tuesday (76%). Worst: Monday (62%).

Smarter routing

Nearby airports that run more on time

  • IAH → SNA 87% chance on time

    George Bush Intercontinental Airport to John Wayne Orange County International Airport · 1,094 flights a year · 30 mi from your airports · yours: 73%

    Rank flightsFares

  • HOU → LGB 83% chance on time

    William P. Hobby Airport to Long Beach International Airport · 503 flights a year · 60 mi from your airports · yours: 73%

    Rank flightsFares

  • IAH → LAX 82% chance on time

    George Bush Intercontinental Airport to Los Angeles International Airport · 5,294 flights a year · 47 mi from your airports · yours: 73%

    Rank flightsFares

  • HOU → ONT 82% chance on time

    William P. Hobby Airport to Ontario International Airport · 362 flights a year · 24 mi from your airports · yours: 73%

    Rank flightsFares

On time by month

All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.

J
78
F
86
M
69
A
76
M
68
J
44
J
51
A
60
S
73
O
66
N
72
D
67

What delays this route

  • Late-arriving aircraft60%
  • Airline (crew, maintenance, boarding)29%
  • Air traffic control and airport volume9%
  • Severe weather2%

Share of delay minutes by the cause airlines report to the US DOT.

Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure

IAH to ONT questions

What time of day is best to fly IAH to ONT?
Noon to 3 PM: 74% of flights arrived on time, against 60% for departures 3 to 6 PM.
Which airline is most on time from IAH to ONT?
United, with a season-adjusted 75% chance of operating and arriving on time over 365 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
What is the worst month for delays on IAH to ONT?
June (44% on time); the best was February (86%), averaged over Jun 2023 to May 2026.
Is this a prediction for my flight?
No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.

More routes from IAH

Live status: FAA delays and ground stops