Route on-time record
ONT to MDW: most on-time flights and the best time to fly
Ontario (Ontario International Airport) to Chicago (Chicago Midway International Airport). 360 nonstop flights in Jun 2025 to May 2026, 90% arrived within 15 minutes and 0.3% were cancelled. The most reliable flight number was Southwest 3658 at 11:55 PM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
ONT → MDW
Ontario to Chicago: 360 nonstop flights a year
On time (12 months)
90%
Cancelled
0.3%
avg delay 5 min
Best time to leave
No clear winner
Most reliable airline
Southwest
90% chance on time
Lowest nonstop fare seen in the next two months: $150 (Southwest 3270 on 2026-10-26). 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 3658
11:55 PM → 5:40 AM3h 45m nonstop
Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 4134; its record covers all of them.
90%
chance on time
- On time (history)
- 91%
- Cancelled
- 0.0%
- Avg arrival delay
- 5 min
- Arrived on time 91% of the time (86 flights, Jun 2025 to May 2026).
- Never cancelled in 87 scheduled flights.
Moderate track record · 86 flights
Find Southwest 3658 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- Southwest Airlines90%
360 flights · 90% on time as flown · 0.3% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM91%
227 flights · avg delay 5 min
- 9 AM to noon89%
37 flights · avg delay 6 min
- After 9 PM91%
88 flights · avg delay 5 min
Best day: Friday (92%). Worst: Wednesday (87%).
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
- Airline (crew, maintenance, boarding)47%
- Air traffic control and airport volume27%
- Late-arriving aircraft26%
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
ONT to MDW questions
- Which airline is most on time from ONT to MDW?
- Southwest, with a season-adjusted 90% chance of operating and arriving on time over 360 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 ONT to MDW?
- July (83% on time); the best was March (95%), 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 ONT
- MDW to ONT (return)
- ONT to PHX 83%
- ONT to DEN 79%
- ONT to SEA 86%
- ONT to LAS 78%
- ONT to DFW 78%
- ONT to SMF 86%
- ONT to OAK 87%
- ONT to SJC 86%
- ONT to SFO 69%
- ONT to SLC 91%
- ONT to ATL 90%
- ONT to PDX 88%
Live status: FAA delays and ground stops