Flight number record

WN 1636

Southwest Airlines · Houston to Dallas

Route: HOU → DAL
Departs: 06:00
Flights: 280
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 17 points better than the national rate of 77.6%. When something does go wrong the average delay runs about 45 minutes. That rests on 280 flights, with a median arrival 10 minutes early.

Set against the rest of the country, WN 1636's record is 17 points better than the US average of 77.6%. That gap is worth roughly 166 fewer late arrivals for every thousand flights.

On time

94.2%

Arrivals under 15 minutes late, of 277 completed flights

Avg delay

45 min

Across delayed arrivals only, not all flights

Cancelled

1.07%

National rate is 1.81%

1 hour+ late

1.1%

National rate is 8.1%

These figures cover 280 flights between July 2025 and June 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.

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 280 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 flights81.4%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

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 5 points better at 94.2%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

WN 1636 next to HOU to DAL

Every carrier on HOU to DAL combined arrived on time 80.9% of the time across 4,060 flights, so WN 1636 is 13 points ahead of it. Across its whole network Southwest Airlines managed 76.6%, which this flight beats by 18 points.

WN 1636 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
WN 1636thin sample	280	94.2%	45 min	1.07%	A
All Southwest Airlines on HOU–DAL	4,060	80.9%	58 min	2.19%	B
All carriers on HOU–DAL	4,060	80.9%	58 min	2.19%	B
Southwest Airlines, whole network	1,390,634	76.6%	54 min	0.89%	B+

Across the year

WN 1636 quarter by quarter

Quarter by quarter WN 1636 held fairly steady: 93.0% in Jul–Sep 2025, 93.9% in Oct–Dec 2025, 96.4% in Jan–Mar 2026 and 94.2% in Apr–Jun 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 202571 flights93.0%
Oct–Dec 202583 flights93.9%
Jan–Mar 202656 flights96.4%
Apr–Jun 202670 flights94.2%

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

By weekday, WN 1636 ranged from 90.9% on Monday to 95.5% on Friday. With about 40 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.

Delay causes

Why WN 1636 runs late

One category carries most of the weight here. National Airspace System accounts for 64% of the 724 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.

National Airspace System
64%
Carrier
33%
Extreme weather
3%

64% 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 466 minutes out of 724, against a national NAS share of 21%. The split is drawn from 724 delay minutes reported on WN 1636.

Cancellations sit at 1.07% against a national 1.81%, 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 1.1% land an hour or more behind schedule, against 8.1% 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 eleven other city pairs in the data, including DAL to SAN (23), DAL to PDX (15) and DAL to SMF (14), 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. 280 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: 94.2% on time and 1.07% 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures