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 3957
SCHEDULED · TYPICAL SCHEDULE
Wednesday, September 30 Today
WN 3957 · STL → MDW
departs 9:30 PM CT · arrives 10:40 PM CT
Forecast issued Wed 8:00 PM ET · 2h before departure
Watch this flight
Other days
Today
Thu 10/1 47%
Fri 10/2 24%
Sat 10/3 18%
Sun 10/4 22%
Mon 10/5 16%
Tue 10/6 16%
Odds over time
Arrive at MDW more than 15 minutes late?
45%
chance · ±0 pts
+19 pts · 24h
HOW SURE WE ARE
High. The odds now come mostly from live FAA and airport data.
Arrive 15+ late
45%
Leave 15+ late
55%
Arrive 1h+ late
15%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
15%
30%
45%
60%
2.9d
2d
1d
12h
6h
Now
Departs
Lands
Arrive at MDW more than 15 minutes late?
Calm-weather odds: 30% · changed +19 pts in 24h
+19 pts
45%
Yes 45%
No 55%
Leave STL more than 15 minutes late?
Calm-weather odds: 35% · changed +20 pts in 24h
+20 pts
55%
Yes 55%
No 45%
Arrive at MDW more than an hour late?
Calm-weather odds: 9% · changed +6 pts in 24h
+6 pts
15%
Yes 15%
No 85%
Cancelled?
Calm-weather odds: 1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to MDW?
On time or early
55%
15–30 min late
26%
30 min–1 hour late
4%
1–2 hours late
12%
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 700 ft, visibility down to 2.5 mi, 1.0 in of rain forecast at MDW that day
↑
9pm departures from STL are often late
↑
Later flights pick up delays from earlier in the day
↓
Wednesdays in September are usually quieter than average
↓
STL usually runs smoothly
Weather at each end
STL (origin)
Gusts 20 kt Ceiling 9,000 ft Visibility 10+ mi Precip none
MDW (destination)
Gusts 21 kt Ceiling 700 ft Visibility 2.5 mi Precip 0.99 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.