We’re talking Fahrenheit here, not Celsius. When you’re roughly above or at freezing, there’s a chance that the ground can have liquid water ready to freeze solid. The sudden drop to near or below zero temperatures, often within 16 to 48 hours, causes groundwater to become solid, expanding rapidly. The force this exerts on the earth and rock surrounding the ice can cause a crack. We mostly don’t see any of this surface cracking because it’s buried under a dusting of snow, but in a few cases, people have observed actual rivets in the ground after hearing the loud boom of a frost quake.