Palms can acclimate to the normal temperature fluctuations they experience.
For instance, in the south and southeast U.S., warm, humid nights are normal. But in the western U.S., evenings are cool. Palm trees in each of these regions are used to their typical temperature fluctuations.
A palm tree’s cold tolerance can differ greatly depending on the species. Tropical palms have fairly low cold tolerance; anything below 50 degrees Fahrenheit can be too much for them. But more temperate species of palm trees can withstand subfreezing temperatures with little or no injury.
Colder temperatures can certainly slow down your palm tree’s root activity and growth rate. But when a palm tree encounters temperatures below what they normally experience, it can cause injury. A palm stressed by cold temperatures is very susceptible to rot issues in its crown and main trunk, as well as nutrient deficiencies, while damages resulting from hard freezes can impact all parts of a palm. Frost alone may only impact exposed parts of a palm.