Schedule: a typical summer Thursday (the flights of Jul 30, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
SOUTHWEST · FLIGHT WN 4121
SCHEDULED · TYPICAL SCHEDULE
Thursday, October 1 Yesterday
WN 4121 · MDW → SMF
departs 9:55 PM CT · arrives 12:25 AM PT
Forecast issued Thu 10:00 PM ET · 1h before departure
Watch this flight
Other days
Thu 10/1
Today 33%
Sat 10/3 26%
Sun 10/4 33%
Mon 10/5 28%
Odds over time
Arrive at SMF more than 15 minutes late?
56%
chance · ±2 pts
+4 pts · 24h
HOW SURE WE ARE
Very high. The odds now come almost entirely from live conditions.
Arrive 15+ late
56%
Leave 15+ late
69%
Arrive 1h+ late
23%
Cancelled
4%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
25%
50%
75%
100%
2.7d
2d
1d
12h
6h
Now
Departs
Lands
Arrive at SMF more than 15 minutes late?
Calm-weather odds: 58% · changed +4 pts in 24h
+4 pts
56%
Yes 56%
No 44%
Leave MDW more than 15 minutes late?
Calm-weather odds: 69% · changed +8 pts in 24h
+8 pts
69%
Yes 69%
No 31%
Arrive at SMF more than an hour late?
Calm-weather odds: 27% · changed +2 pts in 24h
+2 pts
23%
Yes 23%
No 77%
Cancelled?
Calm-weather odds: 4% · changed +3 pts in 24h
+3 pts
4%
Yes 4%
No 96%
How late will it get to SMF?
On time or early
42%
15–30 min late
9%
30 min–1 hour late
23%
1–2 hours late
17%
Over 2 hours late
5%
Cancelled
4%
Gate arrival compared with the scheduled arrival. The ranges add up to 100%.
What’s moving the odds
↑
Cloud base down to 700 ft, visibility down to 1.25 mi, 0.9 in of rain forecast at MDW that day
↑
9pm departures from MDW are often late
↑
Later flights pick up delays from earlier in the day
↓
Mostly benign weather forecast at SMF
↓
Thursdays in October are usually quieter than average
Weather at each end
MDW (origin)
Gusts 21 kt Ceiling 700 ft Visibility 1.25 mi Precip 1.18 in
SMF (destination)
Gusts 5 kt Ceiling none (clear) Visibility 9 mi Precip none
How this resolves
Yes if the gate arrival is more than 15 minutes after the scheduled arrival. Cancelled or diverted flights resolve N/A.
Every question here is display only — there is no betting or money involved. Gate times come from the airline; a cancellation resolves only the “Cancelled?” question, and a diversion voids the delay questions.