Yes, all those are factors---but I think the BIGGEST FACTOR is the fewer hours of daylight. Except for today, the weather has been fantastic in Southern California. But the days are so short that, if you are working, you have little time to ride in the morning or at night.

But I did see some number of riders in Brentwood the other day--in the pitch black before the sun arose. And, of course, what where they doing? They were riding three abreast in a narrow bike lane in high speed traffic. Don't do that.