I'd suggest leaving it over winter, turning it will only stall things.

How much moisture is in your compost will determine whether it freezes to the extent that turning is not possible, the more moisture the faster and harder the pile will freeze. If you maintain adequate levels of moisture, just barely moist, the bacteria should be able to keep working and generating the heat needed to keep the pile from freezing unless you ambient air temperatures drop way below freezing. One thing I have found over the years is that rturning a compost pile on a cold winters day is not really good since it exposes the bacteria to that cold air and could speed up the freezing.

Well I have to say that is a relief. Temperatures are frequently below freezing here in the dead of winter, and tromping through 2 feet of snow to turn the pile sounds like a bit more than I want to deal with! Thanks for the info!

I only turn my pile about twice a year, I make sure its not winter when I turn it. Its hard to turn a block of ice.

Though I have to say, after the pile thaws, its breaks down quickly. The freezing helps breaks down cellular structure and the materials shrink fast.

I'll agree with that.
I also turn mine about twice a year, once in the spring when the frost first goes out of the ground. Sometimes I find a chunk frozen in the middle. I like to think my turning helps the pile to unfreeze. Then I turn again around June.

Actually now that I think of it the pile will get one more turn next month when it transitions from the working side to the resting side. This year I'll have a big resting pile because I had been harvesting compost in the fall but I want to switch to the spring. I let the current workin pile grow extra large and gave the resting side an extra rest. In the spring it'll all go in the garden.

I do hot piles during the warmer months, and warm piles in the winter months. Only the core can be turned over when the temp freezes, so there is not much point to it. One could insulate with plastic blocks or some other material to keep the whole pile warm.

We're a lot further north than you and in zone 3 so just keep adding goodies all winter to the snow covered open bin. When spring comes it thaws and breaks down quickly. I have started using a thick layer of fine wood shavings in the bottom of the bin on top of the earth to try to conserve any nutrients that leach out. They work well and mix with the greens when I turn it.

Leave your bin with room for wintertime additions (the odd fallen branch, kitchen scraps, etc.) and let it freeze if it wants to. Once spring comes, you should be able to get things going again and be none the worse for it having frozen.

With a pile that wasn't sopping wet to begin with, I have found that a crust often forms on the top of the pile inside of my enclosed bins, sometimes in the form of a thick layer of ice, with the lower material still unfrozen. As soon as everything melts, it is interesting to see just how much decomposition has gone on at the bottom of the pile during the winter months...