Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Sat 8:00 PM ET · connections flying that day

Fri, Oct 9: Southwest via Phoenix, leaving 05:15, is the safest bet: 88% chance of reaching Chicago on time.

Nonstops that day

All 1 nonstop →


WN 3153 Southwest Flight history →	ONT 23:55	MDW 05:40	13%	3%	0.6%	83%

Best connections that day, one ticket

Most reliable Quickest (80%+ on time)

Ranked by chance you reach Chicago on time, from each leg’s forecast for the day. Total trip = scheduled departure to arrival (Chicago is 2 h ahead of Ontario). Layovers up to 4 hours. Pick a connection for its 12-month details.


Southwest Details →	ONT 05:30 → LAS 06:35WN 3150	1h 45m Las Vegas	LAS 08:20 → MDW 13:55WN 2271	6h 25m	100%	90%
Southwest Details →	ONT 05:15 → PHX 06:30WN 864	1h 00m Phoenix	PHX 07:30 → MDW 12:50WN 3296	5h 35m	96%	88%
Southwest Details →	ONT 18:35 → SJC 19:45WN 3164	3h 10m San Jose	SJC 22:55 → MDW 05:00 +1WN 3886	8h 25m	99%	85%
Southwest Details →	ONT 18:30 → SMF 19:55WN 3170	3h 55m Sacramento	SMF 23:50 → MDW 05:45 +1WN 3802	9h 15m	98%	84%
Southwest Details →	ONT 06:30 → SJC 07:50WN 383	2h 15m San Jose	SJC 10:05 → MDW 16:10WN 4357	7h 40m	100%	83%
Southwest Details →	ONT 05:50 → DEN 09:05WN 3144	55m Denver	DEN 10:00 → MDW 13:25WN 755	5h 35m	93%	82%
Southwest Details →	ONT 19:30 → OAK 20:50WN 3082	3h 05m Oakland	OAK 23:55 → MDW 06:00 +1WN 3059	8h 30m	95%	78%
Delta Details →	ONT 11:48 → ATL 19:15DL 665	2h 00m Atlanta	ATL 21:15 → MDW 22:15DL 1076	8h 27m	97%	77%

How these are worked out. Each flight’s odds are our forecast for that day (typical odds until the weather forecast covers it); flights of airlines we don’t forecast yet use their 12-month record and are marked. Makes the connection: the first flight’s 12-month lateness curve, scaled so its chance of arriving 15+ min late matches the day’s forecast, at the layover minus the 45-minute minimum (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled × second flight within 15 minutes, each from the day’s forecast.

About this data: forecast odds from our model for Fri, Oct 9 (newest published update); 12-month records from US DOT on-time data, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. JSON