I'm just back from there and it was warm. This winter seems to be a warm one, but make sure you call the visitor center to check the weather condition, also the springs (water sources).
I've talked with someone that's been on that trail in winter several times. What he told me is it's hardly covered in snow, the only time he saw was in a Feb (but last year it's heavy snow all nation wide..). Even if it's snow you don't need snow shoe, from what he told me and my own experiences in the southwest. First of all it's only the lava point is relatively a high alt, where snow a lot of times will turn icy and densely packed, a good pair of ice cleats will do, most of the time the snow will be less than 2".
A overnight will be much more delightful and you got to see a lot. Especially the sunrise/sunset. It really starts to turn truly amazing after campsite 8 after climbing out the potato hollow.