Is it normal in the US to use Celsius for computer inside temperatures, and Fahrenheit for the oven? Aren't you converting back and forth the whole time?
For temperatures near 100C the conversion is easy.
Ovens report temperatures in F, computers in C, shrug.
In general you use F for human temperatures (air temperature, fever, and cooking), and C for everything else. F has a better range for air and body temperature anyway.
Maybe Europeans will switch to F, and Americans will switch to Km :)
(In case you wonder why F is better: The coldest temperature normally experienced by people is 0F and the typical temperature is near 100F. Unlike C where you go negative, and the typical is 20.)