55°: sweat begins
65°: clothes soaked
75°: passing birds bathe on skin
85°: locomote on belly by becoming 1-man slip’n’slide
95°: Full Slime

— gregory erskine (@cat_beltane) July 13, 2016

For me:

55°: Need parka, attempting to set fire to random objects, animals for warmth.
65°: Still need parka, no longer setting fire to animals.
75°: A light jacket is okay if the air is perfectly still.
85°: Comfortable, not warm enough yet to swim. Not sweating yet. AC is not needed.
95°: Pretty good. Warm enough to swim.
100°: It’s getting a little warm; still not sweating.
105°: Remember to turn on AC.
110°: A little sweat appears. Everyone else is dead.