So let's say you want to wear your new spring skirt (an Old Navy steal, by the way, although I snagged it for even less than it's currently on sale for in that link) on the first Monday of spring break, when it's 25 degrees outside with snow on the ground. Because you are SO DONE with winter. You have no desire to pull on jeans and three shirts. You don't even want to put on leggings or tights. You just want to wear your new spring skirt. With bare legs.
So you layer it up with a cami and a long-sleeved tee, and put tall boots on under it. And you wear it anyway.
And that's how you wear your spring clothes when it's still winter outside. (Of course you could also put tights or leggings on under your spring skirt, with your boots.)
Inspiration from Erika, here. (She's adorable, no?)