Schedule: a typical Saturday (the flights of Jul 25, 2026, re-dated). Real flights replace these once the FAA publishes them, usually about a day ahead.
SOUTHWEST · FLIGHT WN 3957
SCHEDULED · TYPICAL SCHEDULE
Saturday, October 3
WN 3957 · STL → MDW
departs 8:50 PM CT · arrives 10:00 PM CT
Forecast issued Thu 5:00 AM ET · 65h before departure
Watch this flight
Other days
Today 50%
Fri 10/2 23%
Sat 10/3
Sun 10/4 22%
Mon 10/5 16%
Tue 10/6 16%
Wed 10/7 14%
Odds over time
Arrive at MDW more than 15 minutes late?
20%
chance · ±1 pts
– · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
20%
Leave 15+ late
26%
Arrive 1h+ late
4%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
5.0d
Now
2d
1d
12h
6h
Departs
Lands
Arrive at MDW more than 15 minutes late?
Calm-weather odds: 16% · changed – in 24h
–
20%
Yes 20%
No 80%
Leave STL more than 15 minutes late?
Calm-weather odds: 25% · changed – in 24h
–
26%
Yes 26%
No 74%
Arrive at MDW more than an hour late?
Calm-weather odds: 3% · 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 MDW?
On time or early
80%
15–30 min late
9%
30 min–1 hour late
7%
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
↑
Later flights pick up delays from earlier in the day
↑
8pm departures from STL are often late
↑
Arrivals into MDW at that hour are often late
↓
Mostly benign weather forecast at STL
↓
Mostly benign weather forecast at MDW
Weather at each end
STL (origin)
Gusts 9 kt Ceiling none (clear) Visibility 10+ mi Precip none
MDW (destination)
Gusts 8 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.