No. I can't imagine planting onions at onset of winter. But, it depends on what planting zone you are in. It also depends on the type of onion. Specific varieties will bulb according to day length, and all are categorized as short, long, or intermediate day length bulbs. Plant the wrong bulb at the wrong time in your zone, and you will have pitiful results. I should talk. I never seem to get it right, in spite of having this bit of knowledge. If you are getting ads for onions, IMO, walk away. If you don't walk away, run!
http://extension.oregonstate.edu/gardening/onion-bulb-formation-strongly-linked-day-length
http://extension.oregonstate.edu/gardening/onion-bulb-formation-strongly-linked-day-length