STL to DEN flight delays & on-time performance
Nonstop flights from St. Louis Lambert International Airport to Denver International Airport · 770 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at STL or DEN right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from St. Louis (STL) to Denver (DEN) arrived on time 76% of the time in Aug 2025 – Jul 2026, worse than the 78% national average.
- 0.3% were cancelled, and 9% arrived an hour or more late.
- United Airlines was the most punctual airline here (78% on time); Southwest Airlines was the least (73%).
- Departures scheduled around 6am did best (96% on time); around 5pm did worst (48%).
- Tuesday was the most reliable day to fly (81% on time) and Monday the least (72%).
- The largest source of delay minutes was late-arriving aircraft (43%).
Which airline is most on time from STL to DEN?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| SkyWest AirlinesRegional airline operating flights for United Express, Delta Connection, American Eagle and Alaska. | 91% | 0.9% | 7 min | 2.8% | 111 |
| United Airlines | 78% | 0.5% | 19 min | 9.1% | 1,099 |
| Frontier Airlines | 76% | 0.7% | 20 min | 10.7% | 291 |
| Southwest Airlines | 73% | 0.0% | 17 min | 8.6% | 2,175 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 5am91%372 flights
- 6am96%161 flights
- 7am92%118 flights
- 8am86%293 flights
- 9am83%288 flights
- 10am82%104 flights
- 11am82%143 flights
- 12pm82%144 flights
- 1pm80%335 flights
- 2pm81%210 flights
- 3pm69%143 flights
- 4pm55%365 flights
- 5pm48%213 flights
- 6pm56%253 flights
- 7pm74%199 flights
- 8pm77%169 flights
- 9pm65%119 flights
- 10pm51%47 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday72%0.4% cancelled
- Tuesday81%0.2% cancelled
- Wednesday79%0.0% cancelled
- Thursday74%0.4% cancelled
- Friday74%0.3% cancelled
- Saturday74%0.2% cancelled
- Sunday74%0.4% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Late-arriving aircraft43%
- Air traffic control & airport congestion32%
- Airline (crew, maintenance, cleaning, fueling)21%
- Extreme weather4%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Airline (crew, maintenance, cleaning, fueling)60%
- Extreme weather40%
- Air traffic control & airport congestion0%
- Security0%
STL to DEN: common questions
- How often are STL to DEN flights on time?
- 76% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from St. Louis to Denver cancelled?
- 0.3% of scheduled flights were cancelled (10 of 3,676).
- How long are typical delays?
- Across all flights the average arrival delay was 17 min (early arrivals count as zero). Flights that were late arrived 67 min behind schedule on average, and 8.8% of flights were an hour or more late.
- How long is taxi time at STL?
- Flights on this route spent 14 min taxiing from the gate to takeoff on average.
Related routes
Return trip: DEN to STL — 78% on time
More flights from St. Louis
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: STL → DEN, nonstop flights by US airlines that report to the DOT. How we calculate this.