Schedule: a typical summer Monday (the flights of Jul 27, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
SOUTHWEST · FLIGHT WN 3909
SCHEDULED · TYPICAL SCHEDULE
Monday, October 5
WN 3909 · STL → DEN
departs 5:35 AM CT · arrives 6:50 AM MT
Forecast issued Fri 7:00 PM ET · 60h before departure
Watch this flight
Other days
Today 3%
Sat 10/3 5%
Sun 10/4 2%
Mon 10/5
Odds over time
Arrive at DEN more than 15 minutes late?
3%
chance · ±1 pts
– · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
3%
Leave 15+ late
3%
Arrive 1h+ late
<1%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
3%
6%
9%
12%
6.3d
Now
2d
1d
12h
6h
Departs
Lands
Arrive at DEN more than 15 minutes late?
Calm-weather odds: 2% · changed – in 24h
–
3%
Yes 3%
No 97%
Leave STL more than 15 minutes late?
Calm-weather odds: 3% · changed – in 24h
–
3%
Yes 3%
No 97%
Arrive at DEN more than an hour late?
Calm-weather odds: <1% · changed – in 24h
–
<1%
Yes <1%
No 99%
Cancelled?
Calm-weather odds: <1% · changed – in 24h
–
<1%
Yes <1%
No 100%
How late will it get to DEN?
On time or early
96%
15–30 min late
2%
30 min–1 hour late
<1%
1–2 hours late
<1%
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
↑
Other factors
↑
DEN is busy at that time
↓
Early flights usually leave on time
↓
5am departures from STL are usually not late
Weather at each end
STL (origin)
Gusts 8 kt Ceiling none (clear) Visibility 10+ mi Precip none
DEN (destination)
Gusts 18 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.