To prepare oneself for the outdoors by adding or removing layers of clothing.
In wintertime, the word "winterize" may be used, instead, to more specifically define the act of preparing oneself for the
cold winter weather
outside by putting on
one's coat, hat, scarf, boots, and/or gloves.
Sam and his friends are about to
go outdoors, but he hasn't finished getting himself ready clothing-
wise.
Sam to his friends: "Hold on guys... I
still need to weatherize!"