Saturday, October 10 · typical odds for a Saturday (too early for a weather forecast) · issued Sun 8:00 PM ET · connections flying that day

Sat, Oct 10: one nonstop, WN 3557 at 16:31, with a 11% chance of arriving 15+ min late.

Nonstops that day

All 1 nonstop →


WN 3557 Southwest	PWM 16:31	MDW 18:20	11%	4%	0.7%	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 1 h behind Portland). Layovers up to 4 hours. Pick a connection for its 12-month details.


Delta Details →	PWM 11:38 → MSP 13:58DL 1766	2h 40m Minneapolis	MSP 16:38 → MDW 18:18DL 4714 · flown by Endeavor	7h 39m	99%	59%
Delta Details →	PWM 12:50 → DTW 14:50DL 426	3h 17m Detroit	DTW 18:07 → MDW 18:25DL 4677 · flown by Endeavor	6h 39m	98%	57%

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 Sat, Oct 10 (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