16-Week San Antonio Marathon Training Plan

The 2026 San Antonio Marathon is scheduled for December 6, 2026, so the 16-week window opens around August 16, 2026. Treat that as the outside edge of the window, then line week one up with the plan's normal weekly rhythm.

Use this window when you have a running base and want several weeks before the hardest marathon-specific work begins. The extra month over a 12-week plan creates more room for gradual long-run growth and recovery. The course does not change the opening load you can handle, so choose from your current mileage and recent longest run before adding race-specific terrain.

Use the first month to establish consistency, then make long runs progressively more specific to the race's terrain and conditions. The course rehearsal should grow with the plan, not appear all at once in peak week. Humidity is the first thing to train for. A December start near 61F with 86% humidity sounds mild and doesn't run mild, because sweat won't evaporate and your effort at any given pace sits higher than the thermometer suggests. Rehearse your fluid and sodium plan in humid conditions, not just warm ones.

Do not double weeks or cram missed mileage into the remaining calendar. Use your current mileage, recent longest run, experience, goal, and available days to choose a plan that can enter at an appropriate point while preserving the taper.

No, and that's the most common mistake runners make about it. The loop climbs 909 feet and descends 902, running between 622 and 814 feet, for a net change of about seven feet. Nothing is steep, but the constant rolling adds up and the bill arrives after mile 20.

Warmer and much stickier than most winter marathons. Race morning norms are near 61F with 86% humidity, an average high of 66F and an average low of 44F. Humidity rather than temperature is what slows people here, because sweat stops evaporating and perceived effort climbs at any given pace.