Yellowstone Next Week - Freezing Temps Concern

According to my FIL who was a manager for the Dept Of Agriculture, rapid freezing occurs at 26 deg F. And that means in an hour or two for a water hose. But up in the thirties it is not an issue if the temps are above freezing during the day, most of the time. We had a water hose freeze a few weeks ago outside Bryce, was not watching the weather closely. No big problem, thawed out in a couple hours, no damage.