Wesleyan has gorgeous weather for about four months out of the year. In between, there is snow, but let's talk about the pretty months first! Fall is absolutely stunning, especially if you're coming from a place with no seasons (well, no "visible" seasons). When the leaves change, it's like a crazy explosion of reds, yellows, and oranges. Spring is great because you've just been super cold for a really long time and then everything gradually melts away, and it's warm enough to wear shorts again. The first time the sun comes out and it gets up to 50 F, you'll see students sunbathing all around campus.
Winter is cold, but not unbearable. Even when there's a freak snowstorm that covers the campus in multiple feet of snow, everyone knows how to have fun with it (e.g., making a colony of igloos and snow forts). You'll get the kind of winter you would expect from any school in the Northeast, basically—but to all you Californian kids, it's really not that bad.