The peak time in CA in summer is 2 - 5pm. It's driven by office AC. After 5pm many offices up the temperature a few degrees for overnight effectively dropping demand. It can peak again after 7pm due to home AC and washer/dryer/dishwasher but that 2 - 5pm in the height of summer is always the peak.
I imagine the yearly peak might be earlier in the day, because it will occur on very hot days.
The time of day of the yearly peak is more important for capacity planning than the time of day of the daily peak.