Carrier route record

WNBOS→AUS

Southwest Airlines · Boston to Austin

Flights: 282
Period: July 2025 to June 2026
Share of route: 17%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on BOS to AUS draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about 55 minutes behind schedule. Build slack into anything you connect to. That rests on 282 flights, with a median arrival 4 minutes late.

The national on-time rate over the same period is 77.6%, so Southwest on BOS to AUS runs 15 points behind the country as a whole. Across a thousand flights that is about 151 extra late arrivals.

On time

62.5%

Arrivals under 15 minutes late, of 280 completed flights

Avg delay

54 min

Across delayed arrivals only, not all flights

Cancelled

0.71%

National rate is 1.81%

Whole route

72.2%

Every carrier on BOS to AUS, 1,634 flights

These figures cover 282 flights between July 2025 and June 2026. Beyond the headline rate, 12.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Southwest against every carrier on BOS to AUS

Southwest flew 282 of the 1,634 flights on BOS to AUS, about 17% of it. Its 62.5% on time is 10 points worse than the route as a whole, which runs 72.2%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 74.9% to Southwest at 62.5%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on BOS to AUS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	988	74.9%	93 min	2.63%	C
JetBlue Airwaysthin sample	364	72.5%	61 min	1.10%	C
Southwest Airlines (this page)thin sample	282	62.5%	54 min	0.71%	D+

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 33 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am6 flights—
8am–11am56 flights80.4%
11am–2pm92 flights75.6%
2pm–5pm121 flights47.1%
5pm–8pm7 flights—
8pm–5am—

Scale runs 40% to 85%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 80.4% of the time, against 47.1% for the afternoon window. That is 33 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 121 flights scheduled in it.

Across the year

Southwest on BOS to AUS through the year

Jul–Sep 202584 flights48.8%
Oct–Dec 202564 flights54.7%
Jan–Mar 202652 flights80.0%
Apr–Jun 202682 flights72.0%

Scale runs 40% to 85%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 62.5% on time across 282 flights.

Southwest on BOS to AUS did not run the same all year. Its best quarter was Jan–Mar 2026 at 80.0% on time and its weakest Jul–Sep 2025 at 48.8%, a swing of 31 points on roughly 71 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 75.0% on time and Sunday the weakest at 49.0%. 26 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 55% of the 5,699 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.

Late-arriving aircraft
55%
Carrier
27%
National Airspace System
18%

55% 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 5,699 reported delay minutes here, that single category outweighs weather by 55 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 5,699 reported delay minutes.

The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 80.4% on time here.

Cancellations are rare at 0.71%, below the national 1.81% 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.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.9% of arrivals land a full hour or more behind schedule, against 8.1% 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.

At 1,698 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg is a different operation and performs like one: it runs 54.7% on time across 282 flights, 8 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 8 points of difference.

One caution: this is a thin sample. 282 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on BOS to AUS

Put together: treat all of this as provisional. 282 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 62.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 280 completed flights over 12 months sit behind that.

Where to go next

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