HELP! I Lost MY PET FERRET!

Someone left the garage door open at night and we suddenly can't find our frettchen and we know it's sure because my dad sagte he's sure that he felt someone furry beside his feet. I'm so worried cause my mom sagte it's gonna rain tonight and we can't go further cause it's dark.
Does anyone know what I should do? He's gonna be so cold and I hope he doesn't get far and die.