It really depends on what you mean by peak demand. From the grid’s perspective a home with rooftop solar has zero demand during peak solar production.
However, that’s ignoring the home actually uses electricity during that period it’s demand simply isn’t something the utility can make money from.
Similarly, transmission losses increase as temperatures rise which requires more production to offset those losses. From the perspective of a natural gas power plant that load is just as real as actual customer demands because utilities need to pay for it.
Finally, time zone boundaries and suburbs being on the east or west of cities on the coast make a noticeable difference. https://www.dailymail.co.uk/sciencetech/article-2572317/Are-...
