For the other Americans that came into the thread hoping to see a conversion:
10c = 50f
30c = 86f
Edit: I'd like to note that 10c is a very reasonable temperature for shorts. I'm a Minnesotan (basically Canada lite (please annex us)), people start raising eyebrows at around 0C
0C? Fellow Minnesotan here and I've definitely seen plent of people wearing shorts at temps below -5C. But I'm also in a college town so that may change things.
I once amusedly watched girls sunbathe in bikinis at St. Lawrence University with patches of snow nearby in, I think March.
Conversely, I personally wore shorts and a tee one fine vacation in Florida around Christmas. It was 60f, and everybody was running around in jackets looking like they were in Chicago in January.