It might not be an absolute must have for everyone, but it made for a better blog title. I would highly recommend a yellow jacket for the spring. It could be a rain slicker by Shipley & Halmos or J. Crew, a poplin blazer or a pull over, like this one by 45rpm. I think you can even go with a bright yellow or a more muted tone, either way it adds an element of spring color while remaining functional. Especially in these transitional months heading into spring when it's still dark and rainy, a yellow jacket will brighten up your day. I find yellow compliments a lot of the colors I am already wearing so it would be easy to throw in the mix. I don't personally like to add a ton of color into an item I can't take off either, so keeping it on the outerwear is also a good idea for minute to minute versatility. Go find one.