Freezing temperatures are very likely tonight as temperatures are expected to be at or below 32 degrees for a few hours early Sunday morning.  Though it certainly is the time of year for cold weather, the freeze tonight is only possible because certain conditions are going to be met.  For temperatures to fall, one of these has to occur: 1) a blast of cold air pumps in behind a cold front.  2) Winds must be very light with clear skies.
    The current overnight situation involves the latter of the two.  Calm winds allow for heat to rise pretty efficiently.  Clear skies mean all the heat that's trying to rise isn't trapped near the surface.  If only one of these conditions were met, no freeze would take place, simply because it just isn't cold enough like it is in the Northern states.
    Freezing levels should only last a few hours, but remember the 4 P's:  Plants, pets, pipes, and people.