The issues on winter entrances are:
mice
robbers
ventilation
snow
dead bees piling up on the bottom
I closed all my bottom entrances off now, but when I had them I reduced them down to about an inch, to keep out the robbers, with 1/4" hardware cloth covering that to keep out the mice and a notch in the inner cover or some other kind of top entrance for top ventilation and an entrance that won't get blocked by snow or dead bees.