Schedule: a typical Wednesday (the flights of Jul 29, 2026, re-dated). Real flights replace these once the FAA publishes them, usually about a day ahead.
SOUTHWEST · FLIGHT WN 3979
SCHEDULED · TYPICAL SCHEDULE
Wednesday, September 30 Today
WN 3979 · STL → SAT
departs 9:20 PM CT · arrives 11:30 PM CT
Forecast issued Wed 10:00 AM ET · 12h before departure
Watch this flight
Other days
Today
Thu 10/1 56%
Fri 10/2 38%
Sat 10/3 20%
Mon 10/5 18%
Tue 10/6 15%
Odds over time
Arrive at SAT more than 15 minutes late?
29%
chance · ±0 pts
+3 pts · 24h
HOW SURE WE ARE
Good. The odds now lean mostly on firmed-up weather forecasts.
Arrive 15+ late
29%
Leave 15+ late
30%
Arrive 1h+ late
6%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
15%
30%
45%
60%
2.8d
2d
1d
Now
6h
Departs
Lands
Arrive at SAT more than 15 minutes late?
Calm-weather odds: 19% · changed +3 pts in 24h
+3 pts
29%
Yes 29%
No 71%
Leave STL more than 15 minutes late?
Calm-weather odds: 34% · changed −2 pts in 24h
−2 pts
30%
Yes 30%
No 70%
Arrive at SAT more than an hour late?
Calm-weather odds: 4% · changed +2 pts in 24h
+2 pts
6%
Yes 6%
No 94%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 100%
How late will it get to SAT?
On time or early
71%
15–30 min late
12%
30 min–1 hour late
11%
1–2 hours late
5%
Over 2 hours late
2%
Cancelled
<1%
Gate arrival compared with the scheduled arrival. The ranges add up to 100%.
What’s moving the odds
↑
Cloud base down to 1,400 ft forecast at SAT that day
↑
Later flights pick up delays from earlier in the day
↑
9pm departures from STL are often late
↓
Wednesdays in September are usually quieter than average
↓
Mostly benign weather forecast at STL
Weather at each end
STL (origin)
Gusts 14 kt Ceiling 9,000 ft Visibility 10+ mi Precip none
SAT (destination)
Gusts 24 kt Ceiling 1,400 ft Visibility 10+ mi Precip 0.05 in
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.