The ideal temperature for watering a Christmas tree is 40 degrees Fahrenheit. This is because colder temperatures will help preserve the tree's freshness and prevent it from drying out too quickly. If the water is too hot, it can cause the tree's needles to fall off prematurely. It is also important to avoid watering the tree excessively, as this can lead to root rot and other issues. Instead, aim to water the tree just enough to keep it well-hydrated and healthy throughout the holiday season.