Schedule: a typical Thursday (the flights of Jul 30, 2026, re-dated). Real flights replace these once the FAA publishes them, usually about a day ahead.
DELTA · FLIGHT DL 1239
SCHEDULED · TYPICAL SCHEDULE
Thursday, October 1
DL 1239 · SEA → SLC
departs 7:50 PM PT · arrives 10:55 PM MT
Forecast issued Tue 6:00 PM ET · 53h before departure
Watch this flight
Other days
Today 22%
Wed 9/30 14%
Thu 10/1
Fri 10/2 25%
Sun 10/4 26%
Mon 10/5 18%
Odds over time
Arrive at SLC more than 15 minutes late?
24%
chance · ±2 pts
– · 24h
HOW SURE WE ARE
Moderate. The odds now blend history with early weather forecasts.
Arrive 15+ late
24%
Leave 15+ late
22%
Arrive 1h+ late
4%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
2.9d
Now
2d
1d
12h
6h
Departs
Lands
Arrive at SLC more than 15 minutes late?
Calm-weather odds: 22% · changed – in 24h
–
24%
Yes 24%
No 76%
Leave SEA more than 15 minutes late?
Calm-weather odds: 22% · changed – in 24h
–
22%
Yes 22%
No 78%
Arrive at SLC more than an hour late?
Calm-weather odds: 3% · changed – in 24h
–
4%
Yes 4%
No 96%
Cancelled?
Calm-weather odds: <1% · changed – in 24h
–
<1%
Yes <1%
No 99%
How late will it get to SLC?
On time or early
75%
15–30 min late
12%
30 min–1 hour late
8%
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
↑
7pm departures from SEA are often late
↑
SEA is busy at that time
↓
Mostly benign weather forecast at SEA
↓
Mostly benign weather forecast at SLC
Weather at each end
SEA (origin)
Gusts 7 kt Ceiling 3,900 ft Visibility 9 mi Precip none
SLC (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.