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 3509
SCHEDULED · TYPICAL SCHEDULE
Sunday, October 4
WN 3509 · SMF → SAN
departs 6:10 PM PT · arrives 7:40 PM PT
Forecast issued Fri 6:00 PM ET · 51h before departure
Watch this flight
Odds over time
Arrive at SAN more than 15 minutes late?
47%
chance · ±8 pts
−1 pt · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
47%
Leave 15+ late
38%
Arrive 1h+ late
10%
Cancelled
<1%
MOSTLY HISTORY
WEATHER FORECASTS
LIVE
IN THE AIR
0%
20%
40%
60%
80%
6.0d
Now
1d
12h
6h
Departs
Lands
Arrive at SAN more than 15 minutes late?
Calm-weather odds: 37% · changed −1 pt in 24h
−1 pt
47%
Yes 47%
No 53%
Leave SMF more than 15 minutes late?
Calm-weather odds: 37% · changed +0 pts in 24h
+0 pts
38%
Yes 38%
No 62%
Arrive at SAN more than an hour late?
Calm-weather odds: 10% · changed +0 pts in 24h
+0 pts
10%
Yes 10%
No 90%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to SAN?
On time or early
52%
15–30 min late
21%
30 min–1 hour late
16%
1–2 hours late
7%
Over 2 hours late
3%
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
↑
SAN is prone to delays
↑
This flight has been late 41% of the time recently
↓
Mostly benign weather forecast at SAN
↓
Mostly benign weather forecast at SMF
Weather at each end
SMF (origin)
Gusts 7 kt Ceiling none (clear) Visibility 10+ mi Precip none
SAN (destination)
Gusts 12 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.