Best time to fly out of Chicago O'Hare (ORD)

The early-flight folk wisdom holds up at Chicago O'Hare: departures in the Before 6am band left on time 89.8% of the time, against 62.1% in the 10pm–12am band. These are historical odds, not forecasts. The records say what happened on this schedule over three years; they know nothing about tomorrow’s thunderstorm.

Data through June 2026 · Bureau of Transportation Statistics

On-time rate by hour and day

On this page, “on time” means a departure that pushed back less than 15 minutes behind its scheduled time — the Bureau of Transportation Statistics definition, and the one airlines are held to.

Share of departures that left on time, by hour band and day of week.
Departure time MonTueWedThuFriSatSun
Before 6am 88 91 92 92 89 88 89
6–8am 88 90 92 90 89 89 89
8–10am 83 86 86 85 82 83 82
10am–12pm 78 82 82 80 77 79 77
12–2pm 78 81 81 79 77 79 76
2–4pm 75 79 77 75 73 78 72
4–6pm 69 75 73 70 69 74 66
6–8pm 68 73 70 67 67 70 65
8–10pm 65 70 68 62 62 68 62
10pm–12am 61 66 62 61 63 69 57
fewer left on time more left on time

The steadiest stretch at ORD was Before 6am — 89.8% of departures left on time across 9,332 flights. The weakest was 10pm–12am at 62.1%. 6–8am departures from ORD left on time 89.6% of the time across 91,658 flights; 6–8pm departures, 68.4% across 136,135. That is a gap of 21.2 points, and it is the whole case for the early flight.

The year at ORD

July was the hard month at ORD: 66.9% of departures left on time, across 77,830 flights. October was the easy one at 82.2%. Each month pools three years of that month, so a single bad week does not decide it.

Share of departures that left on time, by calendar month. Best month in green, worst in amber. The hairline sits at the overall rate, 76.4%.
Departure on-time share at ORD by calendar month
Month Share departures that left on time Flights
January 74% 67,095
February 80.8% 65,080
March 75.8% 78,241
April 78.5% 82,988
May 75.8% 86,568
June 71.7% 85,222
July 66.9% 77,830
August 73.8% 78,937
September 80.9% 76,098
October 82.2% 79,119
November 81.7% 71,492
December 75.2% 71,122

Airlines at ORD

Every airline with at least 100 departures from ORD, busiest first. These are that airline’s departures from this airport only — its record across the country sits on its own page.

Airline Left on time Typical delay Cancelled Departures
United Airlines 78.1% 71 min 1.1% 279,602
SkyWest Airlines 74.3% 87 min 2.4% 186,962
American Airlines 71.8% 82 min 1.7% 162,337
Envoy Air 79% 59 min 1.9% 123,316
Republic Airways 83.8% 71 min 2.3% 70,990
Delta Air Lines 78.2% 93 min 1.6% 32,351
Spirit Airlines 69.8% 75 min 2.2% 20,572
Southwest Airlines 76.8% 60 min 1.3% 18,221
Alaska Airlines 73.5% 60 min 1.2% 9,420
Frontier Airlines 69.1% 102 min 2.9% 8,935
PSA Airlines 63% 137 min 6.6% 3,619
JetBlue Airways 75.7% 102 min 2% 3,368

What delays out of ORD were put down to

Airlines file a reason with every arrival running 15 minutes late or more. Across 228,679 flights that departed ORD and ran 15 minutes late or more, the delay minutes break down with 40.4% put down to late-arriving aircraft and 30.7% to airline operations.

Late-arriving aircraft 40.4% Airline operations 30.7% Air traffic & airport volume 20.5% Severe weather 8.3% Security 0.1%
  • Late-arriving aircraft 40.4%
  • Airline operations 30.7%
  • Air traffic & airport volume 20.5%
  • Severe weather 8.3%
  • Security 0.1%

Late-arriving aircraft is the knock-on category: the plane came in late, so it went out late again. It is why a 7am problem in Newark is still a problem in Denver at dinnertime, and why it is usually the biggest slice on the bar.

If you are connecting through ORD

Of 919,665 scheduled arrivals into ORD, 75.3% reached the gate less than 15 minutes behind schedule. Of the 207,234 arrivals that ran late, 50.8% were no more than 45 minutes behind — which is the difference between a tight connection and a new boarding pass.

Work out a specific layover — pick the airport and the minutes you have, and the tool reads the same arrival records back as a share.

Busiest routes out of ORD

Ranked by flights, with the share that arrived on time at the far end. Where a route carries enough flights for a page of its own the chip goes there; otherwise it goes to the destination airport.

ORD in one number

Chicago O'Hare (ORD)

Rank 4 of 363 US airports by departures. Steadiest stretch of the day: Before 6am. Hardest month: July.

July 2023–June 2026 · 903,561 departures flown

76.4% of departures left on time

Questions about ORD

What is the best time of day to fly out of Chicago O'Hare?
Before 6am. Departures in that band left on time 89.8% of the time across 9,332 flights, July 2023 through June 2026 — the best of the ten bands in the day. The 10pm–12am band was the weakest at 62.1%.
Is the early flight out of ORD really more reliable?
6–8am departures from ORD left on time 89.6% of the time across 91,658 flights; 6–8pm departures, 68.4% across 136,135. That is a gap of 21.2 points, and it is the whole case for the early flight.
What is the worst month to fly out of ORD?
July: 66.9% of the departures that flew left on time, with 77,830 scheduled. October was the other end of the year at 82.2%. Each figure pools three years of that calendar month.
Which airline is most on time at ORD?
Republic Airways — 83.8% of its 70,990 departures from ORD left on time. PSA Airlines sat at the other end at 63% over 3,619 flights. Only airlines with at least 100 departures here are ranked.
How often are flights cancelled at ORD?
1.8% of scheduled departures were cancelled over July 2023 through June 2026. Cancellations are counted against everything scheduled, not against everything that flew — a rate that looks small still adds up to real people in a rebooking line.