Schedule: a typical summer Sunday (the flights of Jul 26, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
SOUTHWEST · FLIGHT WN 1221
SCHEDULED · TYPICAL SCHEDULE
Sunday, October 4 Today
WN 1221 · BOS → DEN
departs 12:35 PM ET · arrives 3:05 PM MT
Forecast issued Sun 6:00 AM ET · 7h before departure
Watch this flight
Odds over time
Arrive at DEN more than 15 minutes late?
18%
chance · ±0 pts
−4 pts · 24h
HOW SURE WE ARE
Good. The odds now lean mostly on firmed-up weather forecasts.
Arrive 15+ late
18%
Leave 15+ late
26%
Arrive 1h+ late
4%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
15%
30%
45%
60%
5.6d
2d
1d
12h
Now
Departs
Lands
Arrive at DEN more than 15 minutes late?
Calm-weather odds: 23% · changed −4 pts in 24h
−4 pts
18%
Yes 18%
No 82%
Leave BOS more than 15 minutes late?
Calm-weather odds: 22% · changed +1 pt in 24h
+1 pt
26%
Yes 26%
No 74%
Arrive at DEN more than an hour late?
Calm-weather odds: 4% · changed −1 pt in 24h
−1 pt
4%
Yes 4%
No 96%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 100%
How late will it get to DEN?
On time or early
81%
15–30 min late
4%
30 min–1 hour late
11%
1–2 hours late
2%
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
↑
This flight has been late 27% of the time recently
↑
12pm departures from BOS are often late
↑
WN's recent on-time record
↓
Gusts to 25 kt forecast at DEN that day
↓
Early flights usually leave on time
Weather at each end
BOS (origin)
Gusts 15 kt Ceiling 1,100 ft Visibility 6 mi Precip 0.13 in
DEN (destination)
Gusts 25 kt Ceiling 7,500 ft 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.