Schedule: a typical summer Friday (the flights of Jul 31, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
SOUTHWEST · FLIGHT WN 4879
SCHEDULED · TYPICAL SCHEDULE
Friday, October 2
WN 4879 · SJC → ONT
departs 6:35 AM PT · arrives 7:55 AM PT
Forecast issued Fri 10:00 PM ET · 12h after departure
Watch this flight
Other days
Fri 10/2
Today 3%
Mon 10/5 2%
Fri 10/9 2%
Odds over time
Arrive at ONT more than 15 minutes late?
2%
chance · ±0 pts
−7 pts · 24h
HOW SURE WE ARE
Very high. The odds now come almost entirely from live conditions.
Arrive 15+ late
2%
Leave 15+ late
4%
Arrive 1h+ late
<1%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
3%
6%
9%
12%
3.5d
2d
1d
12h
6h
Departs
Lands
Arrive at ONT more than 15 minutes late?
Calm-weather odds: 2% · changed −7 pts in 24h
−7 pts
2%
Yes 2%
No 98%
Leave SJC more than 15 minutes late?
Calm-weather odds: 4% · changed −6 pts in 24h
−6 pts
4%
Yes 4%
No 96%
Arrive at ONT more than an hour late?
Calm-weather odds: <1% · changed −5 pts in 24h
−5 pts
<1%
Yes <1%
No 99%
Cancelled?
Calm-weather odds: <1% · changed −1 pt in 24h
−1 pt
<1%
Yes <1%
No 99%
How late will it get to ONT?
On time or early
97%
15–30 min late
1%
30 min–1 hour late
0%
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
↓
Early flights usually leave on time
↓
6am departures from SJC are usually not late
Weather at each end
SJC (origin)
Gusts 5 kt Ceiling 700 ft Visibility 4 mi Precip none
ONT (destination)
Gusts 11 kt Ceiling none (clear) Visibility 8 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.