Schedule: a typical summer Saturday (the flights of Jul 25, 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
Saturday, October 3 Tomorrow
WN 4121 · MDW → SMF
departs 8:35 PM CT · arrives 11:05 PM PT
Forecast issued Fri 7:00 PM ET · 27h before departure
Watch this flight
Other days
Today 31%
Sat 10/3
Sun 10/4 33%
Mon 10/5 28%
Odds over time
Arrive at SMF more than 15 minutes late?
27%
chance · ±1 pts
+1 pt · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
27%
Leave 15+ late
31%
Arrive 1h+ late
6%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
5.0d
2d
Now
12h
6h
Departs
Lands
Arrive at SMF more than 15 minutes late?
Calm-weather odds: 31% · changed +1 pt in 24h
+1 pt
27%
Yes 27%
No 73%
Leave MDW more than 15 minutes late?
Calm-weather odds: 30% · changed +1 pt in 24h
+1 pt
31%
Yes 31%
No 69%
Arrive at SMF more than an hour late?
Calm-weather odds: 6% · changed +0 pts in 24h
+0 pts
6%
Yes 6%
No 94%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to SMF?
On time or early
72%
15–30 min late
13%
30 min–1 hour late
8%
1–2 hours late
5%
Over 2 hours late
<1%
Cancelled
<1%
Gate arrival compared with the scheduled arrival. The ranges add up to 100%.
What’s moving the odds
↑
This flight has been late 45% of the time recently
↑
8pm departures from MDW are often late
↑
Later flights pick up delays from earlier in the day
↓
Mostly benign weather forecast at MDW
↓
Mostly benign weather forecast at SMF
Weather at each end
MDW (origin)
Gusts 8 kt Ceiling none (clear) Visibility 10+ mi Precip none
SMF (destination)
Gusts 7 kt Ceiling none (clear) Visibility 10+ 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.