[ajuc]

My parents care a lot about "przymrozek" - which is when it gets sub-zero C at night and you need to cover the plants and close the greenhouse doors and put a heater there so the plants survive. They give warnings in radio when this happen outside of regular winter months.

There's also special warning for drivers if it was sub-zero because then the water on the roads freezes and it's very hard to break.

I'd say it's way more important a distinction than anything that F makes obvious.