Many snowmobile trails across the state are open some are in good condition and others in poor condition I don't think any are in excellent condidtion yet though.
Some Marathon County trails opened on New Years Eve. The northeast zone includes trails north of Hwy 29 and east of I-39. Even though the trails are open they are in poor to fair condition so ride with caution.
Wood County snowmobile trail information can be found at http://www.co.wood.wi.us/Departments/Parks/Snowmobiling.aspx. As of right now only Kellner area trails are open.
If you have any other information on snowmobile conditions and open trails please comment below