Despite all my gradeschool teachers telling me to get ready because the metric system was coming (this was back in 1980), the United States still uses Fahrenheit to tell temperature.
The rest of the world, however, uses Celsius. So a few months back, I started thinking in Centigrade.
The "official" formula to convert between Fahrenheit and Celsius is sort of complex:
[°C] = ( [°F] - 32 ) × 5/9
Maybe some people can easily multiply by 5/9 without a calculator, but I'm not one of them. But there's an easier way, and it's you can figure out in your head:
[°C] = [°F]-30/2.
So if it's 70°F, it's 20°C. [ 70-30 = 40. 40/2 = 20 ]
This isn't an exact conversion (the official conversion puts 70*F at 21.1*C), but it's close enough to know if you need a jacket or a T-shirt.
Here's what you need to know about Celsius.
- 0: Cold. Jacket required. And maybe some layers.
- 10: Chilly. A jacket is a good idea.
- 15: Cool. You might want to bring a jacket just in case.
- 20: Temperate. No jacket necessary unless you get cold easily.
- 25: Warm. You should be fine in a T-shirt.
- 30: Hot. Definitely T-shirt weather.
There you have it. A simple way for those of us raised on Fahrenheit to gauge the temperature in Celsius.
And remember, don't believe everything they tell you in school.
Photo by Flickr user CipherN. CC BY 2.0.