"Two layers of pants, four layers of shirts, a big coat and go buy a face mask and lots of gloves," says Lisa Weingarg.
She's one of 10,000 that are going to take part in the hot chocolate 15k and 5k race this Sunday. On Friday and Saturday, Union Station will be filled by runners registering and grabbing goodie bags, with hoodies to help keep the cold out.
"Layer, layer, layer like three or four layers," says runner Craig Evans. "Make sure the outer couple ones zip because if you do get warm you can let some air in there. Cause they all let hold in all the air. Definitely a hat cause all your heat goes out your head."
With a Sunday morning start time temperature of five degrees pending, trotters tried on race wear in preparation.
"Just wearing multiple layers," Stephanie Wainright, a race manager. "Make sure you're covering your feet very well, your face, sunglasses, just keeping warm and wearing non cotton layers."
Santa will be bringing his cold temps with him when Union Station brings back real trains and a winter fest.
"Train rides across Union Station, we have ice sculpting, petting zoos," says Tom Lyons, Union Station VP of Sales and Marketing. "There`s just a lot of fun things to do to get you out of that cabin fever for the weekend."
Like the Postal Service, neither snow nor rain will stop these runners from the sweet success of crossing the finish line.
"They receive a finisher`s mug at the end which has hot chocolate and chocolate fondue and dippables. So instead of a finisher`s medal you get a finishers mug filled with all of your chocolate treats," says Wainright.
That`s worth going out into the cold for.