Schedule: a typical summer Friday (the flights of Jul 31, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
SOUTHWEST · FLIGHT WN 3978
SCHEDULED · TYPICAL SCHEDULE
Friday, October 2 Today
WN 3978 · STL → SAT
departs 8:10 AM CT · arrives 10:15 AM CT
Forecast issued Fri 10:00 AM ET · 1h after departure
Watch this flight
Other days
Today
Mon 10/5 10%
Odds over time
Arrive at SAT more than 15 minutes late?
11%
chance · ±0 pts
−8 pts · 24h
HOW SURE WE ARE
Very high. The odds now come almost entirely from live conditions.
Arrive 15+ late
11%
Leave 15+ late
9%
Arrive 1h+ late
3%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
3.5d
2d
1d
12h
6h
Departs
Lands
Arrive at SAT more than 15 minutes late?
Calm-weather odds: 8% · changed −8 pts in 24h
−8 pts
11%
Yes 11%
No 89%
Leave STL more than 15 minutes late?
Calm-weather odds: 9% · changed −7 pts in 24h
−7 pts
9%
Yes 9%
No 91%
Arrive at SAT more than an hour late?
Calm-weather odds: 3% · changed −1 pt in 24h
−1 pt
3%
Yes 3%
No 97%
Cancelled?
Calm-weather odds: <1% · changed −1 pt in 24h
−1 pt
<1%
Yes <1%
No 99%
How late will it get to SAT?
On time or early
88%
15–30 min late
3%
30 min–1 hour late
5%
1–2 hours late
2%
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
↑
Cloud base down to 400 ft, 0.5 in of rain forecast at SAT that day
↑
SAT is prone to delays
↑
Other factors
↓
Arrivals into SAT at that hour are usually not late
↓
Early flights usually leave on time
Weather at each end
STL (origin)
Gusts 17 kt Ceiling 600 ft Visibility 9 mi Precip 0.01 in
SAT (destination)
Gusts 16 kt Ceiling 200 ft Visibility 0.25 mi Precip 0.33 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.