I try to remember: 0 = freezing 10 = chilly 20 = comfy 30 = warm 40 = scorching.

30's hot, 20's pleasing, 10 is not, and 0's freezing.

Also fun:

FAHRENHEIT

  0: Very cold    
  100: Very hot  
CELSIUS

  0: Moderately cold
  100: Dead
KELVIN

  0: Dead
  100: Dead