Find the outfit underneath
Choose the clothes you expect to wear during the milder part of the day. Trousers with a long-sleeved top, or a dress with a light knit, might be a useful starting point. Look at this combination on its own. If it only feels finished beneath a coat, adjust the base before adding more warmth.
Check the forecast for the places and times you will actually be outside. A short walk to transport is different from spending the morning outdoors. Use that distinction to decide whether you need another layer or simply a warmer coat for the first part of the journey.
Add pieces you can remove separately
A cardigan, overshirt or zip layer lets you change the amount you are wearing without replacing the whole outfit. Try the complete combination fastened and move your arms. Too many thick layers can make the shoulders uncomfortable even if each piece fits well on its own.
A scarf may provide a small adjustment, but think about where it will go when you take it off. Keep accessories together in a bag pocket rather than carrying several loose items. If you will remove your coat for most of the day, its weight and folded size become part of the choice.
Rehearse the warm version too
Take off the outer pieces and put them in the bag you plan to carry. If everything does not fit, change one layer before leaving. Consider whether a lighter knit plus a coat is easier than a very heavy jumper. Keep the return journey in mind as well: the temperature may fall again before you get home. A flexible outfit gives you something useful to put back on, rather than leaving you with clothes that only suit lunchtime.
