Route on-time record
STL to ORD: most on-time flights and the best time to fly
St Louis (St. Louis Lambert International Airport) to Chicago (Chicago O'Hare International Airport). 3,060 nonstop flights in Jun 2025 to May 2026, 71% arrived within 15 minutes and 2.9% were cancelled. The most reliable flight number was American 3128 at 5:51 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
STL → ORD
St Louis to Chicago: 3,060 nonstop flights a year
On time (12 months)
71%
Cancelled
2.9%
avg delay 28 min
Best time to leave
Before 9 AM
80% on time vs 56% 6 to 9 PM
Most reliable airline
American
78% chance on time
Lowest nonstop fare seen in the next two months: $102 (American 1997 on 2026-10-23). 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 · American 3128
5:51 AM → 7:21 AM1h 30m nonstop
Local times, typical schedule. Last flown 2026-05-20.
89%
chance on time
- On time (history)
- 95%
- Cancelled
- 2.3%
- Avg arrival delay
- 16 min
- Arrived on time 95% of the time (42 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
- Short track record (42 flights), so its score leans on the airline's record at this hour.
Limited track record · 42 flights
Find American 3128 fares Opens this date on Aviasales#2 · American 1223
6:00 AM → 7:28 AM1h 28m nonstop
Local times, typical schedule. Last flown 2026-04-06.
81%
chance on time
- On time (history)
- 77%
- Cancelled
- 15.4%
- Avg arrival delay
- 110 min
- Arrived on time 77% of the time (22 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
- Short track record (22 flights), so its score leans on the airline's record at this hour.
Limited track record · 22 flights
Find American 1223 fares Opens this date on Aviasales#3 · American 2324
7:00 AM → 8:29 AM1h 29m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as American 2444; its record covers all of them.
81%
chance on time
- On time (history)
- 82%
- Cancelled
- 0.5%
- Avg arrival delay
- 18 min
- Arrived on time 82% of the time (200 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
Strong track record · 200 flights
Find American 2324 fares Opens this date on Aviasales#4 · Envoy 4104 · sold as American Eagle
9:08 AM → 10:40 AM1h 32m nonstop
Local times, typical schedule. Last flown 2026-05-31.
80%
chance on time
- On time (history)
- 91%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 91% of the time (11 flights, Jun 2025 to May 2026).
- Short track record (11 flights), so its score leans on the airline's record at this hour.
Limited track record · 11 flights
Find 9:08 AM flight fares Opens this date on Aviasales#5 · Republic 4460 · sold as American Eagle, Delta Connection or United Express
9:37 AM → 11:05 AM1h 28m nonstop
Local times, typical schedule. Last flown 2026-04-06.
77%
chance on time
- On time (history)
- 79%
- Cancelled
- 9.5%
- Avg arrival delay
- 16 min
- Arrived on time 79% of the time (19 flights, Jun 2025 to May 2026).
- Short track record (19 flights), so its score leans on the airline's record at this hour.
Limited track record · 19 flights
Find 9:37 AM flight fares Opens this date on Aviasales#6 · Envoy 4135 · sold as American Eagle
8:54 AM → 10:22 AM1h 28m nonstop
Local times, typical schedule. Last flown 2026-05-20.
76%
chance on time
- On time (history)
- 81%
- Cancelled
- 0.0%
- Avg arrival delay
- 56 min
- Arrived on time 81% of the time (47 flights, Jun 2025 to May 2026).
- Never cancelled in 47 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
- 65% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 47 flights
Find 8:54 AM flight fares Opens this date on Aviasales#7 · United 1008
6:00 AM → 7:30 AM1h 30m nonstop
Local times, typical schedule. Last flown 2026-05-31.
76%
chance on time
- On time (history)
- 82%
- Cancelled
- 0.0%
- Avg arrival delay
- 27 min
- Arrived on time 82% of the time (11 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
- Short track record (11 flights), so its score leans on the airline's record at this hour.
Limited track record · 11 flights
Find United 1008 fares Opens this date on Aviasales#8 · Envoy 3562 · sold as American Eagle
8:00 AM → 9:31 AM1h 31m nonstop
Local times, typical schedule. Last flown 2026-04-06.
76%
chance on time
- On time (history)
- 76%
- Cancelled
- 3.3%
- Avg arrival delay
- 16 min
- Arrived on time 76% of the time (29 flights, Jun 2025 to May 2026).
- Cancelled 3.3% of the time (1 of 30).
- Leaves in this route's most on-time window (Before 9 AM: 80% on time; 6 to 9 PM: 56%).
- Short track record (29 flights), so its score leans on the airline's record at this hour.
Limited track record · 29 flights
Find 8:00 AM flight fares Opens this date on Aviasales#9 · Republic 3686 · sold as American Eagle, Delta Connection or United Express
9:10 AM → 10:40 AM1h 30m nonstop
Local times, typical schedule. Last flown 2026-04-29.
75%
chance on time
- On time (history)
- 71%
- Cancelled
- 0.0%
- Avg arrival delay
- 14 min
- Arrived on time 71% of the time (21 flights, Jun 2025 to May 2026).
- Short track record (21 flights), so its score leans on the airline's record at this hour.
Limited track record · 21 flights
Find 9:10 AM flight fares Opens this date on Aviasales#10 · Envoy 3815 · sold as American Eagle
2:36 PM → 4:05 PM1h 29m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Envoy 3622; its record covers all of them.
73%
chance on time
- On time (history)
- 78%
- Cancelled
- 0.0%
- Avg arrival delay
- 32 min
- Arrived on time 78% of the time (41 flights, Jun 2025 to May 2026).
- Never cancelled in 41 scheduled flights.
- Lands inside ORD's trouble window: 44% of its 243 ground stops and delay programs started between 2 PM and 8 PM.
- Short track record (41 flights), so its score leans on the airline's record at this hour.
Limited track record · 41 flights
Find 2:36 PM flight fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- American Airlines78%
559 flights · 82% on time as flown · 2.0% cancel
- Envoy Air (sold as American Eagle)73%
700 flights · 75% on time as flown · 2.4% cancel
- Republic Airways (sold as American Eagle, Delta Connection or United Express)72%
441 flights · 73% on time as flown · 3.6% cancel
- United Airlines66%
495 flights · 66% on time as flown · 1.6% cancel
- SkyWest Airlines (sold as United Express, Delta Connection, American Eagle or Alaska)61%
865 flights · 63% on time as flown · 4.4% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM80%
982 flights · avg delay 23 min
- 9 AM to noon76%
246 flights · avg delay 19 min
- Noon to 3 PM69%
534 flights · avg delay 30 min
- 3 to 6 PM67%
865 flights · avg delay 31 min
- 6 to 9 PM56%
431 flights · avg delay 37 min
Best day: Saturday (80%). Worst: Friday (73%).
Smarter routing
Nearby airports that run more on time
STL → MDW 80% chance on time
St. Louis Lambert International Airport to Chicago Midway International Airport · 1,706 flights a year · 15 mi from your airports · yours: 69%
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.
What delays this route
- Air traffic control and airport volume32%
- Late-arriving aircraft30%
- Airline (crew, maintenance, boarding)30%
- Severe weather7%
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
STL to ORD questions
- What time of day is best to fly STL to ORD?
- Before 9 AM: 80% of flights arrived on time, against 56% for departures 6 to 9 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from STL to ORD?
- American, with a season-adjusted 78% chance of operating and arriving on time over 559 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 STL to ORD?
- July (67% on time); the best was February (83%), 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 STL
- ORD to STL (return)
- STL to ATL 85%
- STL to DEN 75%
- STL to LGA 75%
- STL to MCO 78%
- STL to DCA 73%
- STL to DFW 74%
- STL to PHX 76%
- STL to LAS 79%
- STL to DAL 77%
- STL to DTW 83%
- STL to MSP 80%
- STL to CLT 83%
Live status: FAA delays and ground stops