Originally Posted by Brulosopher
It can is all I'm saying, you only know if you measure though. A long time ago, I was fermenting beer in a closet with ambient 68F; the wort got up to 76F at full kraeusen. Jet fuel.
Ah, this makes more sense. In a closet, the ambient could be quite a bit different from the temperature of the outside of the fermenter. I'd be surprised if the center of the wort could be that much higher than the outside edge, but it could easily be that much higher than an uncontained ambient.
In my fridge, except when the compressor is running, the wort and air pretty quickly reach equilibrium. In my closet, the wort (measured via a stick-on thermometer strip) is often fairly different from the air temperature. Just having the air contained and insulated makes a big difference!