hmm...I am normally an extra small and ordered a small for layers - I probably would have fit in an extra small with the layers...but the sleeves were just about right in the sense that there is the additional thumb hole in the inner lining that you can use. If you doing outdoor sports and like to layer then the large might be alright, if you will typically wear it around, then I would stay at a medium.... I hope that helps? I added a photo.
Zelda from Vermont-
I'll try to answer with my own sizing. While I usually order larger pants from Columbia (I usually wear a 6-8, so order an 8 in Columbia), I have found the tops are pretty true to size for my frame. This coat flares out a little to give room for a traditional women's figure (hip room) so I didn't need to size up. If you are smaller on the top than on the bottom like me, I bet you would be ok with a Medium, especially if you don't need to layer. Since Vermont is colder than it is here in Oregon, and you want to layer, you might be happier with the Large to accommodate a sweater or fleece comfortably. good luck!
I think this jacket runs a bit on the smaller side. I would order up especially if you plan on wearing a sweater or something heavy. I initially bought a small for my daughter but had to return it for a medium.