Oops, it doesn't look like 'park on a windy day' is a national day..

Other days

hoodie

Hoodie Day
cursing

Cursing Day
polyamory

Polyamory Day
gum

Gum Day
first love

First Love Day
buddy

Buddy Day
girl friend

Girl Friend Day
cat girl

Cat Girl Day
comfy

Comfy Day
ruby

Ruby Day