Well there is a tendency to still use Fahrenheit during summer like "it's in the 80s", and "it's in the 90s" this month, but most use Celcius for winters when it gets below freezing. There must be a grey area in the 50s and 60s F. Both approaches often seen in headlines. :)

I'm a physicist and I still feel compelled to die on the following hill, re: Fahrenheit---it just maps better to human perception:

30s: Wear a heavy coat

40s: Wear a light coat

50s: Wear a jacket

60s: Wear a hoodie

70s: Wear a t-shirt

80s: Wear shorts

Works in C too:

-ve Don't go outside

0s Wear a coat

10s Wear a jacket

20s Wear a t-shirt

30s Don't go outside

-40s too cold

-30s cold

-20s February

-10s beanie optional

-0s can't store non-alcoholic drinks on the balcony

+0s wear waterproof boots

+10s no need to wear a jacket

+20s don't wear more than a t-shirt

+30s can't sleep since my apt. has no AC

Fixed that for northeners you insensitive clod.

What a brilliant comment! In fact, I'd even say it's over 9E+3 photons/s/mm^2/mrad^2/(0.001*Δλ)

c is just easy because 0 is the freezing point.

Miles per Imperial gallon.