Flight number record

WN 1636

Southwest Airlines · Houston to Dallas

Route: HOU → DAL
Departs: 06:00
Flights: 268
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s WN 1636, check with Southwest Airlines.

WN 1636 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 18 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 45 minutes. That rests on 268 flights, with a median arrival 10 minutes early.

Set against the rest of the country, WN 1636's record is 18 points better than the US average of 77.3%. That gap is worth roughly 178 fewer late arrivals for every thousand flights.

On time

95.1%

Arrivals under 15 minutes late, of 265 completed flights

Avg delay

43 min

Across delayed arrivals only, not all flights

Cancelled

1.12%

National rate is 1.89%

1 hour+ late

0.8%

National rate is 8.3%

These figures cover 268 flights between September 2025 and August 2026. The median arrival is 10 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

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Schedule

When WN 1636 flies

WN 1636 is scheduled to leave Houston (HOU) at 06:00 local time and reach Dallas (DAL) at 07:05. That slot held for 228 of the 268 scheduled departures in the data, so the figures below describe one steady operation rather than a number that moved around the clock.

Departs 06:00228 flights85.1%

Scale runs 0% to 100%.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and WN 1636 runs 6 points better at 95.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

WN 1636 next to HOU to DAL

Every carrier on HOU to DAL combined arrived on time 81.6% of the time across 4,039 flights, so WN 1636 is 14 points ahead of it. Across its whole network Southwest Airlines managed 75.7%, which this flight beats by 19 points.

WN 1636 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
WN 1636thin sample	268	95.1%	43 min	1.12%	A
All Southwest Airlines on HOU–DAL	4,039	81.6%	56 min	2.10%	B
All carriers on HOU–DAL	4,039	81.6%	56 min	2.10%	B
Southwest Airlines, whole network	1,391,794	75.7%	53 min	0.92%	B+

Across the year

WN 1636 quarter by quarter

Quarter by quarter WN 1636 held fairly steady: 93.9% in Oct–Dec 2025, 96.4% in Jan–Mar 2026, 94.2% in Apr–Jun 2026 and 97.0% in Jul–Sep 2026. A spread of 3 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202526 flights—
Oct–Dec 202583 flights93.9%
Jan–Mar 202656 flights96.4%
Apr–Jun 202670 flights94.2%
Jul–Sep 202633 flights97.0%

Scale runs 85% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, WN 1636 ranged from 92.5% on Monday to 97.5% on Friday. With about 38 flights behind each day, a spread of 5 points is inside normal variation, so the day you fly is not worth changing for this flight.

Arrival by arrival

How late WN 1636 runs when it is late

The 13 late arrivals split 6 under half an hour, 5 between 30 and 60 minutes, and 2 an hour or more.

15+ min early52 flights19.6%
Within 15 min200 flights75.5%
15–29 min late6 flights2.3%
30–59 min late5 flights1.9%
1–2 hours late1 flights0.4%
2+ hours late1 flights0.4%

Scale runs 0% to 100%.

Share of 265 completed flights by arrival against schedule.

Only 12 of 265 completed flights left 15 minutes late or more, too few to say how often the time is made up.

The worst days

Worst days for WN 1636

The latest arrival of the period was on 18 April 2026, 2 hours 5 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 WN 1636 in the period
Date	Arrived late by	Largest filed cause
18 April 2026	2 hours 5 minutes	National Airspace System
23 May 2026	1 hour 37 minutes	National Airspace System
4 September 2025	55 minutes	Carrier
29 July 2026	49 minutes	Carrier
2 April 2026	41 minutes	National Airspace System

Delay causes

Why WN 1636 runs late

National Airspace System accounts for 55% of the 557 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
55%
Carrier
45%

55% 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 309 minutes out of 557, against a national NAS share of 21%. The split is drawn from 557 delay minutes reported on WN 1636.

Cancellations sit at 1.12% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 0.8% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

The same number turns up on seven other city pairs in the data, including DAL to SAN (23), DAL to PDX (15) and DAL to PHL (13), but none flew often enough under WN 1636 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to HOU to DAL only.

One caution: this is a thin sample. 268 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 WN 1636

For a booking, WN 1636 has one of the better records a US domestic flight can show: 95.1% on time and 1.12% cancelled. That is a base rate, not a promise about any single day.

Where to go next

A flight number here means Southwest Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.

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