Airport month record
STLJUL
St. Louis Lambert International in July 2025
- Departures
- 5,855
- Month
- July 2025
- National, same month
- 71.1%
- Carriers
- 11
Historical statistics for July 2025, not live status or a forecast for this year’s July. For today’s conditions at STL, see live FAA status.
STL in July sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, level with the national rate of 71.1%. The late ones land a little over an hour behind schedule. That rests on 5,855 flights, of which Delta Air Lines flew 506 at 83.2% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 83.2% on time across 506 flights.
Key figures
On time
71.7%
Arrivals under 15 minutes late, of 5,737 completed departures
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.57%
Nationally in July: 2.45%
Whole year
78.0%
STL across all twelve months
These figures cover 5,855 departures from St. Louis Lambert International in July 2025. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.
Against the year
July next to STL's other months
Against STL's own year, July ran 6 points worse than the twelve-month rate of 78.0%, which makes it number eleven of twelve months, best first.
| Month | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| July 2025 (this page) | 5,855 | 71.7% | 73 min | 1.57% | C |
| August 2025 | 5,539 | 79.7% | 71 min | 0.96% | B+ |
| September 2025 | 5,321 | 83.8% | 58 min | 0.34% | B+ |
| October 2025 | 5,611 | 78.5% | 60 min | 0.27% | B+ |
| November 2025 | 5,202 | 80.1% | 76 min | 1.46% | B |
| December 2025 | 5,359 | 74.0% | 75 min | 0.90% | C+ |
| January 2026 | 4,683 | 83.1% | 74 min | 3.46% | B− |
| February 2026 | 4,484 | 84.9% | 64 min | 1.32% | B |
| March 2026 | 5,400 | 75.3% | 74 min | 2.52% | B |
| April 2026 | 5,156 | 80.8% | 65 min | 0.80% | B+ |
| May 2026 | 5,375 | 77.5% | 74 min | 0.84% | B+ |
| June 2026 | 5,463 | 69.0% | 68 min | 1.17% | C |
Departure window
The best time of day to leave STL in July
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 35 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,256 flights88.2%
- 8am–11am1,168 flights84.2%
- 11am–2pm713 flights74.2%
- 2pm–5pm864 flights63.7%
- 5pm–8pm1,095 flights56.4%
- 8pm–5am759 flights53.1%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 53.1% on time, against 88.2% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 1,256 flights scheduled in it.
Across the week, Tuesday is the strongest day at 76.2% on time and Monday the weakest at 64.6%. 12 points is a smaller lever than departure hour, but it is free.
Carrier by carrier
Which airlines ran best at STL in July
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 83.2% of the time; American Airlines manages 71.0%. Sample sizes sit next to every figure, because a two-point gap across 510 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines | 3,750 | 71.4% | 62 min | 0.96% | C+ |
| American Airlines | 510 | 71.0% | 77 min | 2.16% | C |
| Delta Air Lines | 506 | 83.2% | 77 min | 0.79% | B+ |
| Republic Airwaysthin sample | 250 | 70.4% | 69 min | 10.40% | C− |
| SkyWest Airlinesthin sample | 228 | 63.4% | 134 min | 1.75% | D |
| United Airlinesthin sample | 214 | 54.3% | 114 min | 0.47% | F+ |
| Envoy Airthin sample | 130 | 76.7% | 68 min | 0.77% | B+ |
| Alaska Airlinesthin sample | 92 | 71.4% | 43 min | 1.09% | C |
| Frontier Airlinesthin sample | 82 | 68.4% | 120 min | 2.44% | C |
| PSA Airlinesthin sample | 54 | 81.2% | 292 min | 11.11% | B− |
| Spirit Airlinesthin sample | 39 | 84.6% | 79 min | 0.00% | B+ |
The spread between Delta and American is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
Route by route
Busiest routes out of STL in July
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| STL to DEN · Denverthin sample | 352 | 65.5% | 102 min | 1.42% | C |
| STL to ATL · Atlantathin sample | 351 | 81.3% | 74 min | 0.57% | B+ |
| STL to ORD · Chicagothin sample | 289 | 61.3% | 86 min | 1.73% | D |
| STL to LGA · New Yorkthin sample | 225 | 71.9% | 57 min | 8.44% | C− |
| STL to DFW · Dallas-Fort Worththin sample | 222 | 66.0% | 102 min | 3.15% | C− |
| STL to MCO · Orlandothin sample | 209 | 74.3% | 49 min | 1.44% | C |
| STL to DCA · Washingtonthin sample | 200 | 58.5% | 101 min | 7.00% | D− |
| STL to DTW · Detroitthin sample | 188 | 75.8% | 96 min | 1.06% | B |
| STL to CLT · Charlottethin sample | 170 | 74.1% | 74 min | 0.00% | C+ |
| STL to MDW · Chicagothin sample | 169 | 68.3% | 70 min | 0.59% | C+ |
| STL to PHX · Phoenixthin sample | 166 | 76.5% | 77 min | 0.00% | B+ |
| STL to LAS · Las Vegasthin sample | 164 | 74.7% | 79 min | 0.61% | C+ |
| STL to DAL · Dallasthin sample | 162 | 70.4% | 59 min | 1.23% | C |
| STL to BOS · Bostonthin sample | 149 | 65.1% | 63 min | 2.01% | C |
| STL to MSP · Minneapolisthin sample | 146 | 70.6% | 78 min | 1.37% | C |
| STL to HOU · Houstonthin sample | 144 | 81.7% | 67 min | 0.69% | B+ |
| STL to PHL · Philadelphiathin sample | 135 | 66.7% | 58 min | 3.70% | C− |
| STL to BWI · Baltimorethin sample | 127 | 72.6% | 83 min | 2.36% | C |
| STL to SEA · Seattlethin sample | 123 | 67.2% | 43 min | 0.81% | C+ |
| STL to BNA · Nashvillethin sample | 100 | 72.0% | 81 min | 0.00% | C+ |
| STL to TPA · Tampathin sample | 100 | 66.3% | 41 min | 1.00% | C |
| STL to LAX · Los Angelesthin sample | 93 | 77.4% | 114 min | 0.00% | B+ |
| STL to AUS · Austinthin sample | 93 | 73.9% | 71 min | 0.00% | C+ |
| STL to SLC · Salt Lake Citythin sample | 92 | 91.2% | 75 min | 0.00% | A+ |
| STL to MCI · Kansas Citythin sample | 92 | 68.5% | 75 min | 0.00% | C+ |
Delay causes
What held STL up in July
One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 119,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 46%Late-arriving aircraft
- 31%Carrier
- 19%National Airspace System
- 4%Extreme weather
- 0%Security
46% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 119,000 reported delay minutes here, that single category outweighs weather by 11 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 118,943 reported delay minutes.
Cancellations sit at 1.57% against a national 2.45%, which is ordinary. Diversions add another 0.44%.
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.1% of arrivals land a full hour or more behind schedule, against 12.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
What to do with this
Flying from STL in July
For a July trip through STL: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 88.2% on time, and with 10.1% of arrivals an hour or more late, a connection here deserves more slack than the same trip in February would.
Related
Where to go next
- St. Louis Lambert International (STL), the whole year
- STL in August79.7%
- STL in September83.8%
- STL in October78.5%
- STL in November80.1%
- STL in December74.0%
- STL in January83.1%
- STL in February84.9%
- STL in March75.3%
- STL in April80.8%
- STL in May77.5%
- STL in June69.0%
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.