Schedule: a typical summer Wednesday (the flights of Jul 29, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
REPUBLIC · FLIGHT YX 4678
SCHEDULED · TYPICAL SCHEDULE
Wednesday, September 30
YX 4678 · STL → BOS
departs 7:51 PM CT · arrives 11:37 PM ET
Forecast issued Wed 10:00 PM ET · 1h after departure
Watch this flight
Other days
Wed 9/30
Today 33%
Sat 10/3 19%
Sun 10/4 24%
Mon 10/5 30%
Tue 10/6 20%
Wed 10/7 28%
Odds over time
Arrive at BOS more than 15 minutes late?
27%
chance · ±1 pts
+5 pts · 24h
HOW SURE WE ARE
Very high. The odds now come almost entirely from live conditions.
Arrive 15+ late
27%
Leave 15+ late
27%
Arrive 1h+ late
7%
Cancelled
<1%
WEATHER FORECASTS
LIVE
IN THE AIR
0%
20%
40%
60%
80%
2.8d
2d
1d
12h
6h
Departs
Now
Lands
Arrive at BOS more than 15 minutes late?
Calm-weather odds: 27% · changed +5 pts in 24h
+5 pts
27%
Yes 27%
No 73%
Leave STL more than 15 minutes late?
Calm-weather odds: 27% · changed +2 pts in 24h
+2 pts
27%
Yes 27%
No 73%
Arrive at BOS more than an hour late?
Calm-weather odds: 8% · changed +0 pts in 24h
+0 pts
7%
Yes 7%
No 93%
Cancelled?
Calm-weather odds: <1% · changed +0 pts in 24h
+0 pts
<1%
Yes <1%
No 99%
How late will it get to BOS?
On time or early
72%
15–30 min late
7%
30 min–1 hour late
13%
1–2 hours late
5%
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
↑
Arrivals into BOS at that hour are often late
↑
7pm departures from STL are often late
↑
This flight has been late 30% of the time recently
↓
Wednesdays in September are usually quieter than average
↓
YX's recent on-time record
Weather at each end
STL (origin)
Gusts 20 kt Ceiling 9,000 ft Visibility 10+ mi Precip none
BOS (destination)
Gusts 8 kt Ceiling 700 ft Visibility 2 mi Precip 0.02 in
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.