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 3931
SCHEDULED · TYPICAL SCHEDULE
Saturday, October 3 Tomorrow
WN 3931 · SJU → STL
departs 3:35 PM AT · arrives 7:10 PM CT
Forecast issued Fri 6:00 PM ET · 22h before departure
Watch this flight
Odds over time
Arrive at STL more than 15 minutes late?
22%
chance · ±1 pts
−4 pts · 24h
HOW SURE WE ARE
Good. The odds now lean mostly on firmed-up weather forecasts.
Arrive 15+ late
22%
Leave 15+ late
22%
Arrive 1h+ late
5%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
4.7d
2d
Now
12h
6h
Departs
Lands
Arrive at STL more than 15 minutes late?
Calm-weather odds: 22% · changed −4 pts in 24h
−4 pts
22%
Yes 22%
No 78%
Leave SJU more than 15 minutes late?
Calm-weather odds: 19% · changed −4 pts in 24h
−4 pts
22%
Yes 22%
No 78%
Arrive at STL more than an hour late?
Calm-weather odds: 4% · changed +0 pts in 24h
+0 pts
5%
Yes 5%
No 95%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to STL?
On time or early
77%
15–30 min late
12%
30 min–1 hour late
5%
1–2 hours late
4%
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
↑
Later flights pick up delays from earlier in the day
↑
3pm departures from SJU are often late
↑
This flight has been late 20% of the time recently
↓
Mostly benign weather forecast at STL
↓
Saturdays in October are usually quieter than average
Weather at each end
SJU (origin)
Gusts 12 kt Ceiling 4,200 ft Visibility 10+ mi Precip none
STL (destination)
Gusts 10 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.