It's a challenge keeping a young toddler busy during the winter months. At 16 months, ours is not quite at the age where she can really do a lot of crafting or coloring (she's still sneaking off to hide behind our curtains and nibble the crayons occasionally), but we've come up with a few things that keep her busy on the colder days we're stuck inside...
Teach her something! Toddlers this age are like sponges and we've discovered ours LOVES learning. We write letters and numbers on post its and stick them all up on the wall and let her have her way with them. She's already learned most of the alphabet and a bunch of words this way.
Cut out pictures from magazines or just shapes on regular paper, apply glue with a glue stick (or make your own natural glue with flour, sugar, and vinegar) and make a collage. You may have to help a bit at first, but they'll get the hang of it and enjoy seeing something they've created.
Our daughter happens to love balls of any kind so she has quite a few in different colors. We'll quickly hide a few in different places around the house and then give her detailed instructions to find each one. For example we'll say, "The blue ball is behind the curtain in the living room. Can you find it?" She gets a real satisfaction out of showing us that she understands and discovering the hidden object, plus the exercise/game builds and strengthens her vocabulary.
Get out all of your instruments, put on some music or play some if you have a guitar or piano and let them dance. We make up our own lyrics that describe our daughter doing different things like clapping/spinning/waving and she listens and acts out whatever we're singing.
Build a fort and make sure to use LOTS of pillows. Pillows are a big hit with our little girl, so we pile them all in the fort (which is really very simple involving our sofa, 2 kitchen chairs and a big sheet), along with a few books, and a reading companion like her favorite doll.
We definitely welcome other ideas as we can sometimes go through everything on this list in about...an hour. So please, share your own ideas!