As a metric person, I can confirm.
Indoor temperatures are basically 18-22 for most people most of the time.
15-25 covers the whole range of indoor temperatures that people with functioning heat or A/C would see.
For temperatures outside we commonly round to the nearest five:*
- -5 and below: very cold winter weather
- 0 cold winter weather
- 5 mild winter weather
- 10 autumn weather
- 15 spring weather
- 20 summer weather
- 25 beach weather
- 30 heatwave
- 35 and higher heatwave in the Sahara
The only thing I admire of the Fahrenheit scale is that it can round to the nearest 10 and still be a little bit more precise than Celsius with the nearest 5. And when discussing fever temperatures, Celsius needs half degrees and Fahrenheit does not.
But it’s an absolutely awful scale for cooking.
Of course, generations of humans cooked without thermometers or thermostats. You could cook with the Rankine scale if you get used to it .
But let me just say, I don’t think it’s an accident France is both the originator of the Metric system and haute cuisine.
Advanced cooking is as much engineering as it is art.