Quick answer
Winter tubing works on the spring-fed San Marcos River any time the air hits 65°F+. October and November are the sweet spot. Most outfitters close after Labor Day, so plan for DIY. See the full season calendar.
Can You Tube in Winter?
Water temperature is not the issue. The San Marcos and Comal rivers are spring-fed and hold 72°F all year. Air temperature is the issue. On a 70°F Austin afternoon you can absolutely float.
Best River for Winter Tubing
San Marcos. The water is consistent and the float is short enough (3-4 hours) that you can time it for the warmest part of the day. The Guadalupe is fed by Canyon Lake and runs much colder in winter; skip it.
October and November Are Underrated
Crowds drop 80% after Labor Day. Water is still 72°F. Highs in Austin frequently hit 80°F+ through October. If you've never floated outside summer, October is the best window of the year.
What to Wear for Cold-Weather Tubing
- Quick-dry rashguard or thin neoprene top.
- Water shoes (cold rocks at put-in are no joke).
- Dry bag with a fleece, beanie, and warm clothes for after.
- Thermos of coffee or hot tea for the post-float chill.
Cross-check the full packing list and live river conditions before driving out.