What tempwould you condsider cold enough to have to start wrapping your cooling head?

Cold enough I don't want to be outdoors doing RC.

I've never found it necessary in cold temps, at least those above freezing. The combustion chamber gets just as hot as always. Just the fins give off heat faster. So it's not much difference around the sleeve/piston.

I guess if it was far enough below freezing, I might be tempted to wrap it, but that's too cold for me.