Schedule: a typical summer Monday (the flights of Jul 27, 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
Monday, October 5
WN 4121 · MDW → SMF
departs 9:55 PM CT · arrives 12:25 AM PT
Forecast issued Sat 5:00 AM ET · 66h before departure
Watch this flight
Other days
Today 33%
Sun 10/4 35%
Mon 10/5
Fri 10/9 36%
Odds over time
Arrive at SMF more than 15 minutes late?
24%
chance · ±2 pts
– · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
24%
Leave 15+ late
31%
Arrive 1h+ late
4%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
7.0d
Now
2d
1d
12h
6h
Departs
Lands
Arrive at SMF more than 15 minutes late?
Calm-weather odds: 26% · changed – in 24h
–
24%
Yes 24%
No 76%
Leave MDW more than 15 minutes late?
Calm-weather odds: 30% · changed – in 24h
–
31%
Yes 31%
No 69%
Arrive at SMF more than an hour late?
Calm-weather odds: 5% · changed – in 24h
–
4%
Yes 4%
No 96%
Cancelled?
Calm-weather odds: <1% · changed – in 24h
–
<1%
Yes <1%
No 99%
How late will it get to SMF?
On time or early
76%
15–30 min late
9%
30 min–1 hour late
11%
1–2 hours late
3%
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
↑
9pm departures from MDW are often late
↑
This flight has been late 45% of the time recently
↑
Later flights pick up delays from earlier in the day
↓
Mostly benign weather forecast at MDW
↓
Mondays in October are usually quieter than average
Weather at each end
MDW (origin)
Gusts 8 kt Ceiling none (clear) Visibility 10+ mi Precip none
SMF (destination)
Gusts 6 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.