snowflake symmetry earlier this fall. If you want to extend the lessons a bit, consider making a 3D paper snowflake. Does your snowflake have rotational symmetry? Line symmetry?
And before you leave the topic of snow, read Robert Frost's Stopping By Woods on a Snowy Evening. My older kids memorized this poem when they were little. Now I'm working on it with my younger two. The book itself is gorgeous and one that we pull out and read several times each winter.