I guess I'm used to a lot of people on here being from places other than the US, so whenever I mention temperature I point out that I'm using Fahrenheit. I just hate leaving any room for misinterpretation.Some of my American friends do this too, I assume as a courtesy so that this Eurotrash isn't confused. But the overlap is only relevant when the number is less than ~ 40. If it's 80 C outside, you don't have to worry about anything, least of all measurement units.