Hula in the Coola Day is the time to put on a swimsuit and a grass skirt, and go outside to dance the hula! It's supposed to be a mind-over-matter kind of thing, urging us all to think we're feeling warm even if we are really feeling chilly.
(Needless to say, exposure to cold can be dangerous!)
Hula in the Coola reminds me of some other dare-to-bear-the-cold type events, such as Polar Bear Plunges in Canada. The typical Polar Bear Plunge is a group event organized to raise money for charity—and I imagine that Hula in the Coola could be, too!
If you're going to hula dance, you need to know a little something about hula. Check out this and this other video.
Also on this date: