PlainFlights

Route · STL → SLC · 2020–2025 BTS data

St. Louis to Salt Lake City

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), STL to SLC (St. Louis to Salt Lake City) ranks #2001 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

89%
On-time
+10 pts
vs US avg
89 min
Delay when late
6,304
Flights
#2001 of 4927
Corpus placement

Cancelled

0.6%

Best Month

Nov 2024 98%

Worst Month

Jul 2024 78%

Distance

1,156 mi

Carriers

13

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 79 17 1 0 DL
Nov 2025 83 10 0 0 DL
Oct 2025 88 9 0 1 DL
Sep 2025 82 7 1 0 DL
Aug 2025 88 10 1 0 OO,WN,DL
Jul 2025 92 8 0 1 WN,DL
Jun 2025 90 10 2 1 DL,WN
May 2025 86 10 0 0 DL
Apr 2025 76 9 0 1 DL
Mar 2025 80 5 1 0 DL
Feb 2025 65 7 0 0 DL
Jan 2025 66 5 2 0 DL
Dec 2024 73 7 0 0 DL
Nov 2024 82 2 0 0 DL
Oct 2024 84 5 0 0 DL
Sep 2024 81 4 0 0 DL
Aug 2024 86 10 0 0 DL,WN
Jul 2024 91 20 3 0 DL,WN
Jun 2024 87 9 0 0 DL,WN
May 2024 79 7 0 0 DL
Apr 2024 77 13 0 0 DL
Mar 2024 80 9 0 0 DL
Feb 2024 66 9 0 0 DL
Jan 2024 69 11 1 0 DL

STL–SLC seasonal on-time pattern

Best: September (92.5%) · weakest: December (83.6%)

82%84%86%88%90%92%94% JanFebMarAprMayJunJulAugSepOctNovDec 83.6%

Strongest calendar month

September

92.5% on-time · ~91 flights/mo

Busiest calendar month

August

~105 flights/mo avg

Weakest calendar month

December

83.6% on-time · ~84 flights/mo

Cancellation Rate

0.6%

12 of 1,930 flights

Diversion Rate

0.2%

4 of 1,930 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

STL - St. Louis

Full on-time, delay-cause, and seasonal performance for St. Louis, MO.

STL on-time profile

SLC - Salt Lake City

Full on-time, delay-cause, and seasonal performance for Salt Lake City, UT.

SLC on-time profile

Compare the two airports

See STL and SLC side by side on delays, cancellations, and reliability.

Compare STL vs SLC

Origin-hub reliability standing

Among STL's stronger departures

STL → SLC posts a 89% on-time rate, landing in the ≥85% band with 5 of 51 BTS-tracked routes leaving St. Louis. The same hub also shows 45 mid-band and 1 challenged departures · fleet-wide on-time rank #258 of 4927 (highest on-time = #1).

What the Data Says About STL to SLC

St. Louis to Salt Lake City (STL to SLC) is one of the more dependable pairings in the BTS On-Time Performance dataset: a 89% on-time rate across 6,304 flights, with delays that do happen averaging 89.3 minutes. The corridor runs roughly 1,156 miles and is served by 13 carriers. Over the most recent 24 months, 12 of 1,930 flights were cancelled (0.6%) and 4 diverted (0.2%).

The monthly split is wide on this route: Nov 2024 posted the strongest performance at 98% on-time, while Jul 2024 came in at just 78% - a 20-point swing worth factoring into travel timing.

On the multi-year calendar, STL–SLC peaks in September at 92.5% on-time while August carries the heaviest traffic (~105 flights per month) ; the softest month is December at 83.6%, a 8.9-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does STL to SLC rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, STL to SLC ranks #2001 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from STL to SLC? ▼
Flights from St. Louis to Salt Lake City have a 89% on-time rate based on 6,304 flights. The average delay is 89.3 minutes. The best recent month was Nov 2024 with 98% on-time.
What is the cancellation rate for STL to SLC? ▼
Over the last 24 months, 0.6% of flights on this route were cancelled (12 of 1,930 flights) and 0.2% were diverted.
How far is the flight from STL to SLC? ▼
The flight distance from St. Louis (STL) to Salt Lake City (SLC) is approximately 1,156 miles. This route is served by 13 carriers.
When is the best time to fly from STL to SLC? ▼
The best recent month for on-time performance was Nov 2024 (98% on-time). The worst was Jul 2024 (78% on-time). Consider booking during months with historically better performance.

Airports on this route

STL Airport

St. Louis
SLC Airport

Salt Lake City
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using STL–SLC data

STL–SLC runs 10 pts above the national 79% average; the remaining risk is month-to-month swing and carrier mix, not a weak headline rate.

  • Compare STL and SLC airport profiles: delay causes and top routes differ even on the same corridor. STL airport
  • If your dates flex, September (92.5% on-time) beats December (83.6%) on this corridor. Seasonal chart
  • 4 other routes post a similar 89% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.