Which pics are sunset sherbert? I'm running one now, tomorrow will be the end of week three. But you should invest in a small space heater with a thermostat to keep those ladies warm. The cold temps will definitely affect your yields. I'm in the same climate (over the sierras from you, so probably colder actually) and my tent stays at 64-70 right now, but I'm running a 600w hps which puts out some heat. I need to get a space heater for my room, my old one just shit the bed.
I would just pipe in some heat if possible. I personally dont trust space heaters..but if you do invest may I suggest an oil filled one, less chance of a fire.