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 621
SCHEDULED · TYPICAL SCHEDULE
Wednesday, September 30 Today
WN 621 · SJC → BWI
departs 9:40 PM PT · arrives 5:45 AM ET
Forecast issued Wed 2:00 AM ET · 23h before departure
Watch this flight
Other days
Today
Thu 10/1 22%
Sat 10/3 14%
Sun 10/4 21%
Mon 10/5 18%
Tue 10/6 13%
Odds over time
Arrive at BWI more than 15 minutes late?
14%
chance · ±1 pts
+1 pt · 24h
HOW SURE WE ARE
Good. The odds now lean mostly on firmed-up weather forecasts.
Arrive 15+ late
14%
Leave 15+ late
13%
Arrive 1h+ late
3%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
2.7d
2d
Now
12h
6h
Departs
Lands
Arrive at BWI more than 15 minutes late?
Calm-weather odds: 13% · changed +1 pt in 24h
+1 pt
14%
Yes 14%
No 86%
Leave SJC more than 15 minutes late?
Calm-weather odds: 13% · changed +1 pt in 24h
+1 pt
13%
Yes 13%
No 87%
Arrive at BWI more than an hour late?
Calm-weather odds: 3% · changed +0 pts in 24h
+0 pts
3%
Yes 3%
No 97%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 100%
How late will it get to BWI?
On time or early
85%
15–30 min late
9%
30 min–1 hour late
3%
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
↑
Later flights pick up delays from earlier in the day
↑
WN's recent on-time record
↑
9pm departures from SJC are often late
↓
Wednesdays in September are usually quieter than average
↓
Mostly benign weather forecast at SJC
Weather at each end
SJC (origin)
Gusts 13 kt Ceiling none (clear) Visibility 7 mi Precip none
BWI (destination)
Gusts 10 kt Ceiling 6,000 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.