Celsius is easy, everything important is a nice and rounded number: -40°C is freezing point of vodka; -30°C is fucking cold; -20°C is cold but tolerable; -10°C is pleasant winter weather; 0°C is when roads get icy, better be careful; 10°C is pleasant autumn weather; 20°C is room temperature and pleasant spring/summer; 30°C is haaawwt; 40°C is you-must-be-shitting-me hot; 80 to 100°C is good sauna; 110°C is those-crazy-Finns sauna; 120°C is the-bloody-Russians-joined-the-sauna-party; 250°C is pizza oven; 1000°C is ceramics oven; 1500°C is steel smelting. Everything above use K instead; substract 273 to get C if you must.
Fahrenheit is a fucking mess where nothing makes sense and nothing is a rounded number.