Well it would be very unusual for any blackouts to occur in California during the nighttime hours, since it's the heavy use of energy during the workday that drains resources. Energy use appears to peak during the late afternoon/early evening hours and then decline thru the night. That's because: 1) heat is highest at that time; and 2) people are working all day and then go home.
That's not to say a stretch of really, really hot weather wouldn't drain resources so much that it COULD extend into the night, but not likely.
So don't use that as an excuse to boink your significant other by candlelight.....if your looking for an excuse, that is.