Compost question

My compost seems to be inactive - cold and wet. I'm in the Sacramento area and I am used to having a warm, steaming heap. We did have a couple weeks with overnight temps below freezing in January. Is that enough to shut of the "bugs" in my pile? Will it start back up when the weather warms? I'm using a PE cylindrical bin, just like you might make out of chicken wire or somethning. The content is a reasonable mix of browns and greens - I just fed it a bunch of winter grass that I hoed out, and we turned it thoroughly. Still, no activity. Thanks for any hints or guesses. ;-)
Dave ....
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