Yeah, as previous chap said... gets foggy.
And I'll second his advice about staying on the other side of the mountains.
I rented an arrow in LA to do some hour building and the smog was so bad that I had to escape into Arizona and Nevada to get decent weather. I was there for the whole of march and half of april and lost about 2 weeks due rubbish weather - until I went east.
PM me if you want any details.