During a demonstration, one tree had been watered frequently and firefighters could not set it on fire even after they used a torch.
Another one that hadn't been watered frequently caught fire quickly and in just seconds became a fireball that can burn down a house.
"This time of year, because people are using heaters in their home, what's happening is that trees aren't getting watered anymore. They are going to dry out much more quickly," Menlo Park Fire District's Harold Schapelhouman said.
Other holiday dangers lurk in the kitchen. Oil can catch fire in a forgotten pot. If it does, don't put water on it because that causes it to explode in flames.
The same goes for turkey fryers that catch fire.
Also, make sure you have a working fire extinguisher to minimize holiday accidents.