You probably are familiar with this first part. Whether you're a pear, too heavy or an all over hourglass, any coat, jacket or blazer will either fit you in the curvy spots and not the waist or the waist and not the curvy spots. When something does zip up and fit skin tight like a glove, you look like sausage casing, be it you're a size 0, 4 or 18.
Unless you're on a North Pole marine life expedition, in which case you'll be wearing a puffy jacket anyway matching your fellow scientist team, leave your jacket or whatever it is you're wearing up top open. Unbuttoned. Unzipped. Open fully.
I'm from Illinois originally. You women complaining about the cold elsewhere come off ridiculous to me. "Oh no," you say, "Alabama is 32 degrees today!" Try school not getting canceled unless it's something like -25, -30 degrees Fahrenheit in the windchill. NYC, same. Manhattan weather is no problem for me. A few days, it does get cold cold but not Illinois cold. Never Canada cold, I'm told, or Boston cold.
To really get your new open coat look working, wear something nice underneath. A cozy sweater. Blouse. Layering, only as long as the layering isn't too bulky, and then, you can always leave your coat wider open. A warm, tightly worn scarf cuts through any cold getting to you. Gloves, almost always. And my secret I've learned with skirts and dresses: boots and longer coats block the wind out fairly well.
Sure, you could not listen to my advice and look like a ballpark frank in front of your co-workers. Or a new crush! Adding onto this point of thought progression, stuffing yourself in a coat feels really uncomfortable.
Leaving a cost or jacket open allows you to decide how much attention you want on your curves. Wear something low cut, or pair a shorter jacket with a tight skirt. Or bundle up and look super cheesy cute. You aren't on full display with an open jacket!