Dallas in December: A Rolling Course, a Growing Field, and a Pacing Puzzle Worth Solving

Texas' longest-running marathon returns to Dallas City Hall on December 13, with conditions shaping up to be among the most cooperative the race has seen in recent years — clear skies, light wind, and a start-line temperature around 48°F. After two editions that swung between brutal cold and heavy mist, the 2026 field has a genuine opportunity to run well on a course that rewards patience and punishes those who go out too fast.

By the numbers

The race has grown meaningfully across the two most recent editions. The 2025 field reached 3,874 finishers — up from 3,420 in 2024 — with women's participation rising from 1,062 to 1,189. The overall median improved sharply too, from 4:38:08 in 2024 to 4:30:25 in 2025, a swing that likely reflects both better weather (extreme cold in 2025, though brutal in its own way, is often faster than warm humidity) and a maturing field. The top end tightened as well: the top-10% cutoff moved from 3:33:38 to 3:25:46.

How the course runs

The BMW Dallas Marathon is classified as rolling, and the data bear that out. The course carries 446 feet of sustained climbing and 443 feet of sustained descent over 26.2 miles, with a net drop of just 46 feet — essentially neutral. Three stretches define the terrain: a 151-foot climb between miles 3.4 and 7.1 (averaging 0.8%), a sharper 144-foot climb from miles 18.4 to 20.0 (averaging 1.7%), and then a long 177-foot descent from miles 20.6 to 24.8 (averaging 0.8%). That late-race descent arrives just as legs are tiring, which makes the final miles a test of controlled form rather than a free ride.

The 2025 fade curve tells the story clearly. The field ran its fastest segments in the opening miles, then began to slow at the half:

The segment ending at mile 22.4 is the most striking figure in the table — a median of 12:05/mi, coinciding with the tail end of the late climb and the onset of late-race fatigue. The field partially recovers through the descent to the finish, but never recaptures early rhythm.

Pacing patterns

Back-half slowdowns are the norm at every major marathon, and Dallas is no exception — but the magnitude has varied sharply with conditions. In the mist and 95% humidity of 2024, 91% of the field ran positive splits, with an average second-half slowdown of 16.4% and only 161 negative splitters. The frigid 2025 edition — 31°F at the start, winds near 24 mph — still saw 80% of the field fade, though the average slowdown dropped to 11.4% and negative splitters climbed to 471. Cold, dry air tends to preserve aerobic capacity even when it's uncomfortable; thick humidity at race temperature does not. For 2026, conditions sit between those two extremes and lean toward the better end.

The weather question

The forecast for December 13, 2026 — 48°F at the start, clear, wind around 5 mph, 72% humidity — is closer to ideal marathon weather than anything the race has seen in the two most recent editions. Neither the wind chill of 2025 nor the heavy moisture of 2024 appears likely. If the forecast holds, the field should have a real shot at median times closer to — or better than — 2025's 4:30:25.

What it takes

The benchmarks from 2025: a 2:23:45 winning men's time, 2:53:50 on the women's side. Top 10% entry requires finishing under 3:25:46; top 25% under 3:54:09. The median runner crossed in 4:30:25 overall (4:24:09 for men, 4:44:53 for women), and the 75th percentile sat at 5:14:17.

What to watch

The field-size trajectory is the clearest trend to monitor — back-to-back growth from 3,420 to 3,874 suggests the race is drawing a wider audience within the Dallas Marathon Festival weekend. Whether 2026 crosses 4,000 finishers for the first time will be worth tracking. The weather forecast also sets up a potential improvement in the median finish time and in the negative-split count, which jumped from 161 to 471 between the two most recent editions as conditions improved. And the 36K segment — that 12:05/mi median in 2025 — is the course's most honest stress test; how the field handles miles 20 through 23 will tell most of the story by the time runners reach City Hall.