I didn't' have a probe in with the cheese. The grill was on smoke and the main section of the grill was 160-170 whenever I checked. I set that tray right over a pan of ice and the cheese never felt warm to the touch so I'm guessing I was able to keep the warming tray under 100. There was still ice in the pan after two hours. Outside temp was just above 40. I was not so lucky the other day and slightly fatted out some cheddar - it will be destined for cooking - detroit pizza edges, mac & cheese, etc.