Even in the great state of Texas we have cold, rainy weeks. While I feel like curling up under a blanket with a great book, my boys usually prefer bouncing off the walls, the furniture or each other, which doesn't usually end well.
Two indoor things that the boys are enamored with recently are color mixing with droppers and painting with q-tips. Montessori Services sells this whole kit or individual droppers and bottles. We make up a tray with 3 dropper bottles (red, blue, yellow), a watercolor mixing palate (so they have more wells to experiment with colors) and a sponge. I can't tell you the hours that have been spent creating special colors and complementing each other on their color combinations.
I don't know why I haven't tried q-tip painting earlier. It is genius! The small, short q-tip gives them more control than a paint brush and they use a lot less paint. Our stay-within-the-lines son like to outline dot-to-to pictures with dabs, while our other son uses the q-tips to make wild messy streaks, much to his delight. Again, we use cheap watercolor palates with lots of holes and they also experiment with mixing colors.
Another boredom buster suggested by Kat awhile ago was marshmallow/toothpick building. I think we will use this later to practice forming letters.
Best wishes as we all brave the depths of winter!