The short answer
Here is the clear answer.
Santa wears red because it is warm, cheerful, and easy for the North Pole team to spot against miles of snow and a dark Christmas Eve sky.
Red stands out at the North Pole.
The North Pole is filled with white snow, deep green trees, and long blue nights. A bright red coat makes Santa easy to see around the workshop, beside the reindeer, and near the sleigh.
The color also looks warm and welcoming when Santa arrives from a cold rooftop.
The suit is made for serious winter work.
Santa's coat is thick, soft, and flexible enough for climbing in and out of the sleigh. White trim helps seal in warmth, sturdy boots handle icy landings, and deep pockets keep small tools and route notes close.
The elves inspect every seam before the Christmas Eve mission begins.
Christmas colors carry a message.
At Santa's workshop, red means warmth, courage, and generous hearts. Green stands for the trees that stay bright through winter, and gold is the color of lamplight and stars.
Quick North Pole answers
A few more things curious hearts ask
Has Santa always liked red?
Yes. Red has long been Santa's favorite color for warmth, cheer, and visibility in the snow.
Who makes Santa's suit?
Skilled North Pole elves tailor and inspect Santa's Christmas Eve clothes.
Does Santa have more than one red suit?
Yes. A mission this important always has carefully prepared spare clothing.