A cold seizure can happen at any temp. It happens when you run up a two stroke too soon after starting and the piston skirt has begun to expand faster then the rest of the engine .at really cold temps, you could have cold seize issues just as a snowmobile can have.... might also be a good idea to change jetting on the carb but, it should run at any temp..
Jetting richer (or at least move the C clip down a notch or so) is the way to go for cold riding.