The mystery of Fahrenheit revealed (partially)

According to Wikipedia only two countries are using Fahrenheit: the US and Belize (formerly British Honduras). The rest of the world keeps up with the standards...

So for an 'alien' like I am, it is hard to understand the weather forecast, but I came up with a hypotesis: you see, here the actual temperature you feel does not really have to do anything what they say the temperature is. Let me explain: they say it is 74°F which is around 23°C. It's ok, but if you leave the shades and you are under the sun directly, you feel as it was 74 degrees! So if the °F value is above 60 it represents what you feel: Freekin' hot!!*

However the solution below 20°C is still a mystery to me.

BTW, if you needed the very simple conversion formula that anyone could calculate without using a calculator any time (... NOT) is the following:

[°C] = ([°F] − 32) × ⁵⁄₉

[°F] = [°C] × ⁹⁄₅ + 32

Yeah, yeah, summer is here and it's HOT!

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* Rule only applies to California according to the writer's observations.