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.
DELTA · FLIGHT DL 1239
SCHEDULED · TYPICAL SCHEDULE
Wednesday, September 30 Today
DL 1239 · SEA → SLC
departs 7:50 PM PT · arrives 10:55 PM MT
Forecast issued Wed 7:00 AM ET · 16h before departure
Watch this flight
Other days
Today
Thu 10/1 22%
Fri 10/2 25%
Sun 10/4 26%
Mon 10/5 18%
Tue 10/6 16%
Odds over time
Arrive at SLC more than 15 minutes late?
23%
chance · ±3 pts
+7 pts · 24h
HOW SURE WE ARE
Good. The odds now lean mostly on firmed-up weather forecasts.
Arrive 15+ late
23%
Leave 15+ late
21%
Arrive 1h+ late
4%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
10%
20%
30%
40%
2.9d
2d
1d
Now
12h
6h
Departs
Lands
Arrive at SLC more than 15 minutes late?
Calm-weather odds: 25% · changed +7 pts in 24h
+7 pts
23%
Yes 23%
No 77%
Leave SEA more than 15 minutes late?
Calm-weather odds: 21% · changed +5 pts in 24h
+5 pts
21%
Yes 21%
No 79%
Arrive at SLC more than an hour late?
Calm-weather odds: 3% · changed +0 pts in 24h
+0 pts
4%
Yes 4%
No 96%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to SLC?
On time or early
77%
15–30 min late
14%
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
↑
7pm departures from SEA are often late
↑
Later flights pick up delays from earlier in the day
↑
Arrivals into SLC at that hour are often late
↓
Mostly benign weather forecast at SEA
↓
Wednesdays in September are usually quieter than average
Weather at each end
SEA (origin)
Gusts 9 kt Ceiling 3,200 ft Visibility 10+ mi Precip none
SLC (destination)
Gusts 16 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.