ATIS Alerts Smart Flight Search
Find the flight least likely to be delayed
BetaWe rank real flight numbers by how often they flew and arrived on time over the last 12 months, adjusted for your travel month and departure time, then check nearby airports and calmer connections. US airlines and airports.
MDW → STL
Chicago to St Louis: 1,705 nonstop flights a year
On time (12 months)
82%
Cancelled
0.9%
avg delay 11 min
Best time to leave
Before 9 AM
94% on time vs 64% after 9 PM
Most reliable airline
Southwest
81% chance on time
Lowest nonstop fare seen in the next two months: $56 (Southwest 3042 on 2026-11-07). 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 · Southwest 1862
9:00 AM → 10:15 AM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-30.
92%
chance on time
- On time (history)
- 100%
- Cancelled
- 6.5%
- Avg arrival delay
- 1 min
- Arrived on time 100% of the time (29 flights, Jun 2025 to May 2026).
- Cancelled 6.5% of the time (2 of 31).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
- Short track record (29 flights), so its score leans on the airline's record at this hour.
Limited track record · 29 flights
Find Southwest 1862 fares Opens this date on Aviasales#2 · Southwest 1370
1:55 PM → 3:05 PM1h 10m nonstop
Local times, typical schedule. Last flown 2026-05-27.
89%
chance on time
- On time (history)
- 100%
- Cancelled
- 0.0%
- Avg arrival delay
- 1 min
- Arrived on time 100% of the time (16 flights, Jun 2025 to May 2026).
- Departs outside MDW's trouble window (7 AM to 1 PM, when 50% of its 30 ground stops and delay programs started).
- Short track record (16 flights), so its score leans on the airline's record at this hour.
Limited track record · 16 flights
Find Southwest 1370 fares Opens this date on Aviasales#3 · Southwest 2630
7:50 AM → 9:05 AM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 2458; its record covers all of them.
89%
chance on time
- On time (history)
- 90%
- Cancelled
- 0.0%
- Avg arrival delay
- 15 min
- Arrived on time 90% of the time (77 flights, Jun 2025 to May 2026).
- Never cancelled in 78 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 94% on time; After 9 PM: 64%).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
Moderate track record · 77 flights
Find Southwest 2630 fares Opens this date on Aviasales#4 · Southwest 1164
10:15 AM → 11:30 AM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-31.
86%
chance on time
- On time (history)
- 92%
- Cancelled
- 0.0%
- Avg arrival delay
- 3 min
- Arrived on time 92% of the time (24 flights, Jun 2025 to May 2026).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
- Short track record (24 flights), so its score leans on the airline's record at this hour.
Limited track record · 24 flights
Find Southwest 1164 fares Opens this date on Aviasales#5 · Southwest 265
10:30 AM → 11:40 AM1h 10m nonstop
Local times, typical schedule. Last flown 2026-04-04.
84%
chance on time
- On time (history)
- 85%
- Cancelled
- 0.0%
- Avg arrival delay
- 14 min
- Arrived on time 85% of the time (13 flights, Jun 2025 to May 2026).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
- Short track record (13 flights), so its score leans on the airline's record at this hour.
Limited track record · 13 flights
Find Southwest 265 fares Opens this date on Aviasales#6 · Southwest 1422
11:40 AM → 12:55 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-29.
84%
chance on time
- On time (history)
- 83%
- Cancelled
- 0.0%
- Avg arrival delay
- 17 min
- Arrived on time 83% of the time (23 flights, Jun 2025 to May 2026).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
- Short track record (23 flights), so its score leans on the airline's record at this hour.
Limited track record · 23 flights
Find Southwest 1422 fares Opens this date on Aviasales#7 · Southwest 3751
11:15 AM → 12:30 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-04-06.
82%
chance on time
- On time (history)
- 76%
- Cancelled
- 15.0%
- Avg arrival delay
- 9 min
- Arrived on time 76% of the time (17 flights, Jun 2025 to May 2026).
- Departs inside MDW's trouble window: 50% of its 30 ground stops and delay programs started between 7 AM and 1 PM.
- Short track record (17 flights), so its score leans on the airline's record at this hour.
Limited track record · 17 flights
Find Southwest 3751 fares Opens this date on Aviasales#8 · Southwest 577
2:35 PM → 3:50 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-04-06.
81%
chance on time
- On time (history)
- 87%
- Cancelled
- 0.0%
- Avg arrival delay
- 11 min
- Arrived on time 87% of the time (15 flights, Jun 2025 to May 2026).
- Departs outside MDW's trouble window (7 AM to 1 PM, when 50% of its 30 ground stops and delay programs started).
- 72% of its delay minutes came from the plane arriving late from an earlier flight.
- Short track record (15 flights), so its score leans on the airline's record at this hour.
Limited track record · 15 flights
Find Southwest 577 fares Opens this date on Aviasales#9 · Southwest 3144
2:10 PM → 3:25 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-05-29.
76%
chance on time
- On time (history)
- 74%
- Cancelled
- 0.0%
- Avg arrival delay
- 13 min
- Arrived on time 74% of the time (23 flights, Jun 2025 to May 2026).
- Departs outside MDW's trouble window (7 AM to 1 PM, when 50% of its 30 ground stops and delay programs started).
- Short track record (23 flights), so its score leans on the airline's record at this hour.
Limited track record · 23 flights
Find Southwest 3144 fares Opens this date on Aviasales#10 · Southwest 4009
9:55 PM → 11:10 PM1h 15m nonstop
Local times, typical schedule. Last flown 2026-04-06.
71%
chance on time
- On time (history)
- 64%
- Cancelled
- 6.7%
- Avg arrival delay
- 44 min
- Arrived on time 64% of the time (14 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (After 9 PM: 64% on time; Before 9 AM: 94%).
- Departs outside MDW's trouble window (7 AM to 1 PM, when 50% of its 30 ground stops and delay programs started).
- 73% of its delay minutes came from the plane arriving late from an earlier flight.
Limited track record · 14 flights
Find Southwest 4009 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Southwest Airlines81%
1,705 flights · 82% on time as flown · 0.9% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM94%
431 flights · avg delay 4 min
- 9 AM to noon91%
354 flights · avg delay 6 min
- Noon to 3 PM83%
286 flights · avg delay 11 min
- 3 to 6 PM67%
213 flights · avg delay 22 min
- 6 to 9 PM73%
261 flights · avg delay 14 min
- After 9 PM64%
160 flights · avg delay 24 min
Best day: Tuesday (86%). Worst: Sunday (76%).
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