I've made Esme two long-sleeved dresses based off this pattern, all '3T' without any pattern alterations except 'fudging' the sleeve for the missing piece. In August when I made this for her it was too big for her to wear at all!
I think that will be warm this winter and they are a little 'big' (1/2 inch too long sleeve, adjustable zipper in back, slight 'tent' look to the whole waist) so she won't grow out of them too quickly. The 3T toddler shirts she is wearing now are already getting tough to take on and off. I only bought about three (as you can tell by how often they show up, especially the blue one) and am not feeling happy about going up to 4T for a two year old. Honestly, I think they have shrunk from overwashing.. maybe? Maybe I just like clothes with more give in them and room and they don't really plan for that now.
I also have a pattern for a fleece jacket that might come in handy. Another point is that these sleeves are bulkier than a 't-shirt' sleeve which her current coat expects.
We are off to have a yard sale today at a friend's!