my experience is you can wear wind breaking jacket as opposed to down jacket unless such jacket is waterproof and wind breaking. the key things that made you feel cold is wind chill not the low temperatures. to make your body warm you can wear down vest or 抓毛vest, then wear a wind breaking jacket.
therefore ski jacket will do the work, both wind breaking and waterproof. there is actually down jacket with ski jacket materials, eg Columbia, though not cheap.
my kids have been wearing like this in the previous years we went to Korea in winter. no problem.