Carrier route record

WNAUS→BOS

Southwest Airlines · Austin to Boston

Flights: 286
Period: September 2025 to August 2026
Share of route: 17%
Carriers: 3

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

Southwest on AUS to BOS earns an F, which is as low as this site's scale goes for a reason. Only 54.8% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.3%. Late arrivals average roughly 50 minutes. Treat any tight connection here as a coin flip. That rests on 286 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,001 at 69.6% on time.

The national on-time rate over the same period is 77.3%, so Southwest on AUS to BOS runs 23 points behind the country as a whole. Across a thousand flights that is about 225 extra late arrivals.

On time

54.8%

Arrivals under 15 minutes late, of 281 completed flights

Avg delay

52 min

Across delayed arrivals only, not all flights

Cancelled

1.75%

National rate is 1.89%

Whole route

64.5%

Every carrier on AUS to BOS, 1,713 flights

These figures cover 286 flights between September 2025 and August 2026. Beyond the headline rate, 13.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

Southwest against every carrier on AUS to BOS

Southwest flew 286 of the 1,713 flights on AUS to BOS, about 17% of it. Its 54.8% on time is 10 points worse than the route as a whole, which runs 64.5%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 69.6% to Southwest at 54.8%.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 69.6% of the time; JetBlue Airways manages 59.0%. Sample sizes sit next to every figure, because a two-point gap across 426 flights means less than a ten-point one.

On-time performance by carrier on AUS to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,001	69.6%	90 min	2.70%	C
JetBlue Airways	426	59.0%	82 min	3.29%	D−
Southwest Airlines (this page)thin sample	286	54.8%	52 min	1.75%	F

JetBlue Airways cancels 3.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

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 38 points, against 11 points between the best and worst carrier.

5am–8am—
8am–11am70 flights66.7%
11am–2pm177 flights55.7%
2pm–5pm39 flights28.9%
5pm–8pm—
8pm–5am—

Scale runs 20% to 70%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 66.7% of the time, against 28.9% for the afternoon window. That is 38 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 177 flights scheduled in it.

Across the year

Southwest on AUS to BOS through the year

Jul–Sep 202526 flights—
Oct–Dec 202564 flights49.2%
Jan–Mar 202652 flights49.0%
Apr–Jun 202682 flights54.9%
Jul–Sep 202662 flights60.7%

Scale runs 40% to 65%. 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 54.8% on time across 286 flights.

Southwest on AUS to BOS did not run the same all year. Its best quarter was Jul–Sep 2026 at 60.7% on time and its weakest Jan–Mar 2026 at 49.0%, a swing of 12 points on roughly 72 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, Tuesday is the strongest day at 70.3% on time and Sunday the weakest at 46.9%, a spread of 23 points.

Arrival by arrival

How late Southwest on AUS to BOS runs when it is late

The 127 late arrivals split 39 under half an hour, 50 between 30 and 60 minutes, and 38 an hour or more.

15+ min early16 flights5.7%
Within 15 min138 flights49.1%
15–29 min late39 flights13.9%
30–59 min late50 flights17.8%
1–2 hours late29 flights10.3%
2+ hours late9 flights3.2%

Scale runs 0% to 100%.

Share of 281 completed flights by arrival against schedule.

28 of 143 late departures made up the time and arrived on time, 20% of them. 12 flights left on time and still arrived late.

The worst days

Worst days for Southwest on AUS to BOS

The latest arrival of the period was on 30 July 2026, 3 hours 46 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The same cause led on three of the five worst days.

The latest arrivals of Southwest on AUS to BOS in the period
Date	Arrived late by	Largest filed cause
30 July 2026	3 hours 46 minutes	National Airspace System
14 October 2025	2 hours 50 minutes	National Airspace System
20 October 2025	2 hours 27 minutes	Late-arriving aircraft
6 November 2025	2 hours 26 minutes	National Airspace System
14 September 2025	2 hours 18 minutes	Late-arriving aircraft

Delay causes

Why Southwest runs late on this route

National Airspace System accounts for 52% of the 6,536 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
52%
Late-arriving aircraft
25%
Carrier
23%
Security
0%

52% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,395 minutes out of 6,536, against a national NAS share of 21%. The split is drawn from 6,536 reported delay minutes.

Cancellations sit at 1.75% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

13.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 65.6% on time across 286 flights, 11 points above 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 11 points of difference.

One caution: this is a thin sample. 286 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 AUS to BOS

Put together: treat all of this as provisional. 286 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 54.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 281 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures