Thursday, October 8 · typical odds for a Thursday (too early for a weather forecast) · issued Sun 12:00 PM ET · connections flying that day

Thu, Oct 8: WN 4237 at 06:16 is the safest bet, 9% chance of being 15+ min late; the others run 22%.

Nonstops that day

All 2 nonstops →


WN 4237 Southwest	SAN 06:16	MDW 12:10	9%	2%	0.9%	no record
WN 1252 Southwest	SAN 11:56	MDW 17:59	22%	5%	0.9%	no record

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 San Diego). Layovers up to 4 hours. Pick a connection for its 12-month details.


Delta Details →	SAN 06:15 → ATL 13:49DL 729	1h 26m Atlanta	ATL 15:15 → MDW 16:15DL 1728	8h 00m	98%	86%
Southwest Details →	SAN 08:37 → LAS 10:02WN 1848	3h 27m Las Vegas	LAS 13:29 → MDW 19:06WN 5001	8h 29m	100%	76%

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 Thu, Oct 8 (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