I did some research about C and F temperature scales and found out that only in US and a few other smaller countries use F, which I didn't know
Of course you are most comfortable to the system you are used to:
If you're an American and you've ever had a conversation with someone from another country about the weather, you've probably been a little confused when he or she says that the afternoon temperature is a nice 21 degrees. To you, that might sound like a chilly winter day, but to them, it's a pleasantly warm springtime temperature.
That's because virtually every other country in the rest of the world uses the Celsius temperature scale, part of the metric system, which denotes the temperature at which water freezes as 0 degrees, and the temperature at which it boils as 100 degrees. But the U.S. and a few other holdouts – the Cayman Islands, the Bahamas, Belize and Palau – cling to the Fahrenheit scale, in which water freezes at 32 degrees and boils at 212 degrees. That means that the 21 degrees C temperature that we previously mentioned is the equivalent of a balmy 70 degrees F in the U.S.