Airport month record

LASSEP

Harry Reid International in September 2025

Departures: 14,399
Month: September 2025
National, same month: 83.4%
Carriers: 11

Historical statistics for September 2025, not live status or a forecast for this year’s September. For today’s conditions at LAS, see live FAA status.

LAS in September lands a B+, 5 points worse than the national rate of 83.4%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 14,399 flights, of which Delta Air Lines flew 1,250 at 84.4% on time.

Delta Air Lines is the most reliable of the nine carriers covered here at 84.4% on time across 1,250 flights.

On time

78.8%

Arrivals under 15 minutes late, of 14,285 completed departures

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

0.53%

Nationally in September: 0.51%

Whole year

77.9%

LAS across all twelve months

These figures cover 14,399 departures from Harry Reid International in September 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

September next to LAS's other months

Against LAS's own year, September ran level with the twelve-month rate of 77.9%, which makes it number six of twelve months, best first. Either side of it, August ran 79.6% on time and October 77.1%, so this month sits in line with its neighbours.

LAS month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	15,733	72.9%	67 min	1.13%	C
August 2025	14,920	79.6%	59 min	0.50%	B+
September 2025 (this page)	14,399	78.8%	66 min	0.53%	B+
October 2025	15,597	77.1%	62 min	0.31%	B+
November 2025	14,443	79.5%	59 min	1.73%	B
December 2025	14,547	79.9%	59 min	0.60%	B+
January 2026	13,695	83.1%	65 min	1.86%	B
February 2026	12,886	83.1%	58 min	0.88%	B+
March 2026	15,169	78.3%	60 min	1.15%	B
April 2026	14,672	78.8%	54 min	0.40%	B+
May 2026	14,585	74.1%	60 min	0.67%	C+
June 2026	13,704	70.7%	61 min	0.77%	C+

Departure window

The best time of day to leave LAS in September

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,101 flights92.5%
8am–11am3,239 flights87.2%
11am–2pm2,668 flights77.2%
2pm–5pm2,327 flights69.4%
5pm–8pm1,993 flights66.6%
8pm–5am2,071 flights76.0%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.5% of the time, against 66.6% for the evening window. That is 26 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 3,239 flights scheduled in it.

Across the week, Wednesday is the strongest day at 90.0% on time and Friday the weakest at 61.3%. 29 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at LAS in September

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 84.4% of the time; Alaska Airlines manages 76.1%. Sample sizes sit next to every figure, because a two-point gap across 441 flights means less than a ten-point one.

Carriers at LAS in September 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlines	6,794	76.7%	53 min	0.47%	B+
Spirit Airlines	1,344	81.3%	91 min	1.12%	B
Delta Air Lines	1,250	84.4%	76 min	0.00%	B+
United Airlines	1,194	80.5%	60 min	0.17%	B+
American Airlines	1,105	84.4%	101 min	1.09%	B
Frontier Airlines	934	78.6%	81 min	0.75%	B+
Allegiant Air	532	80.0%	77 min	0.00%	B+
Alaska Airlines	441	76.1%	52 min	0.45%	B+
SkyWest Airlines	380	76.3%	68 min	0.79%	B+
JetBlue Airwaysthin sample	275	72.3%	76 min	1.09%	C
Hawaiian Airlinesthin sample	150	74.7%	118 min	0.00%	C+

Delta leads Alaska by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Route by route

Busiest routes out of LAS in September

Routes from LAS in September 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
LAS to LAX · Los Angeles	691	78.2%	55 min	0.43%	B+
LAS to SAN · San Diego	610	72.5%	71 min	0.98%	C+
LAS to DEN · Denver	539	73.0%	68 min	0.19%	C+
LAS to SFO · San Francisco	513	63.2%	44 min	0.39%	D+
LAS to ORD · Chicago	481	77.6%	91 min	0.62%	B+
LAS to SEA · Seattle	441	82.4%	60 min	0.23%	B+
LAS to PHX · Phoenix	431	78.6%	69 min	2.09%	B
LAS to DFW · Dallas-Fort Worth	423	85.9%	101 min	2.13%	A
LAS to SMF · Sacramento	407	77.8%	64 min	0.25%	B+
LAS to ATL · Atlanta	389	88.4%	87 min	0.00%	A+
LAS to SJC · San Jose	375	79.0%	51 min	0.80%	B+
LAS to BUR · Burbankthin sample	352	79.1%	63 min	0.85%	B+
LAS to SNA · Santa Anathin sample	347	77.3%	50 min	1.15%	B
LAS to JFK · New Yorkthin sample	336	80.1%	68 min	0.89%	B+
LAS to RNO · Renothin sample	323	81.3%	63 min	0.62%	B+
LAS to SLC · Salt Lake Citythin sample	314	78.9%	62 min	0.32%	B+
LAS to OAK · Oaklandthin sample	300	70.6%	63 min	0.33%	C+
LAS to PDX · Portlandthin sample	264	79.8%	55 min	0.00%	B+
LAS to IAH · Houstonthin sample	255	85.5%	76 min	0.00%	A+
LAS to DTW · Detroitthin sample	239	82.0%	150 min	0.00%	B+
LAS to EWR · Newarkthin sample	237	77.6%	70 min	0.84%	B+
LAS to AUS · Austinthin sample	218	78.5%	75 min	0.92%	B+
LAS to MDW · Chicagothin sample	212	82.9%	66 min	0.47%	B+
LAS to ONT · Ontariothin sample	201	77.6%	49 min	0.00%	B+
LAS to DAL · Dallasthin sample	197	82.1%	72 min	0.00%	B+

Delay causes

What held LAS up in September

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 198,000 reported delay minutes.

Late-arriving aircraft
40%
Carrier
31%
National Airspace System
25%
Extreme weather
3%
Security
0%

40% 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 198,000 reported delay minutes here, that single category outweighs weather by 12 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 198,402 reported delay minutes.

Cancellations are rare at 0.53%, below the national 0.51% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

6.8% of arrivals land an hour or more late, close to the national 5.4%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.

What to do with this

Flying from LAS in September

For a September trip through LAS: expect 78.8% on time and 0.53% cancelled, going by September 2025. The 5am–8am window was the strongest part of the day.

Harry Reid International (LAS), the whole year
LAS in July72.9%
LAS in August79.6%
LAS in October77.1%
LAS in November79.5%
LAS in December79.9%
LAS in January83.1%
LAS in February83.1%
LAS in March78.3%
LAS in April78.8%
LAS in May74.1%
LAS in June70.7%

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.

Key figures