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 4509
SCHEDULED · TYPICAL SCHEDULE
Monday, October 5
WN 4509 · SAN → SJC
departs 9:30 AM PT · arrives 11:00 AM PT
Forecast issued Sat 9:00 PM ET · 40h before departure
Watch this flight
Other days
Today 13%
Sun 10/4 15%
Mon 10/5
Fri 10/9 18%
Odds over time
Arrive at SJC more than 15 minutes late?
13%
chance · ±1 pts
+1 pt · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
13%
Leave 15+ late
10%
Arrive 1h+ late
3%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
6.5d
2d
Now
1d
12h
6h
Departs
Lands
Arrive at SJC more than 15 minutes late?
Calm-weather odds: 11% · changed +1 pt in 24h
+1 pt
13%
Yes 13%
No 87%
Leave SAN more than 15 minutes late?
Calm-weather odds: 9% · changed +0 pts in 24h
+0 pts
10%
Yes 10%
No 90%
Arrive at SJC more than an hour late?
Calm-weather odds: 2% · 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 99%
How late will it get to SJC?
On time or early
86%
15–30 min late
5%
30 min–1 hour late
5%
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
↑
SAN is prone to delays
↑
9am departures from SAN are often late
↑
Other factors
↓
Mostly benign weather forecast at SAN
↓
Arrivals into SJC at that hour are usually not late
Weather at each end
SAN (origin)
Gusts 16 kt Ceiling 1,700 ft Visibility 9 mi Precip none
SJC (destination)
Gusts 13 kt Ceiling none (clear) Visibility 3 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.