You may remember your jacket, but what about gloves, a scarf, a cap or moisturiser? These are the things people often overlook because they seem less important than the main outfit.
Depending on your destination, you may also need lip balm, sunglasses and sunscreen. Cold weather does not eliminate sun exposure, particularly at higher altitudes or around snow.
Make a separate checklist for these smaller essentials instead of assuming you will remember everything while packing.