Surely, the thing about shorts is that they are cool (temp.-wise) to wear - they are not a winter garment.
It seems to be v.trendy to wear stuff 'inappropriately' at the moment - I mean in 2 years time, we will all be laughing our ducks off at the fact that grown women actually wore flip-flops to the office. And now winter shorts.....
I mean, stand back a minute and think about it whydoncha?