It's a good thing one of the subjects of my last Bonsai 101 class was how to put our bonsai to bed for the winter....
winter arrived a week later.
24*F in mid November.
About a month earlier than normal, we brought everyone around to their winter home.
There they were tucked in close to each other, with straw stuffed around the pots. This will keep the roots at a even constant temperature thru the winter.
A few I have in the garage because they just are not ready for such terribly cold temps this early.