Why compare it to 40°? Because I know what 40° feels like because I've been living in a civilized country with a civilized measurement system all my life. I can tell you that 65° is too hot, because I make my tea with 70° to 80° hot water. Therefore just before that will probably be too hot for my skin.

In the end, there is no objectively better system when it comes to day to day temperatures. But there is one when it comes to science, reliability and universality and that is Celsius.

All international science uses metric and slowly but surely the resistance amongst US universities melts away and they switch to metric as well. Give it another one or two generations and we'll finally be rid of the outdated and arbitrary imperial system!

I can absolutely tell 65°C is too hot, that's 5°C short of what is piped as literal hot water in the taps in my area.

I would not recommend going above 40°C for washing, and there is literally zero issue remembering that. Body temperature of a healthy human is 36,6-36,7°C (97,9-98,1°F), everything above that is hot.

As such, there is literally zero issue figuring 40°C is reasonably hot and 65°C is unreasonably hot, it doesn't take a genius.

Speaking of water, Celsius is obviously superior as a water-based system. I can easily tell temperature in my kettle goes to 100°C (212°F, huh?), or steps down to 90°C (194°F??) or 80°C (176°F??) to brew a perfect cup of tea. When temperature outside goes 0°C (32°F??), I know I can expect ice and snow. And for everything in between, I can make a pretty accurate approximation.

And finally, modern Fahrenheit scale is literally defined through Celsius. It's a scale that is defined as 32°F at the freezing point of water (i.e. 0°C) and 212°F at water boiling point (i.e. 100°C). You're literally using Celsius but make it harder for no reason.

Appreciate you. All I wanted was to have an interesting discussion. People in here acting like I shot the Pope.