Sorry, I didn't really want to get into another pissing match with you, but these are the facts.
Again the earliest sunset in PS is around 4:45pm. Second, as I'd assume anyone knows who lives by the ocean, it is not "pitch dark" at sunset, but as I stated it takes at least an hour to get dark. It does not matter whether it is by a mountain or not, because it's the atmosphere that keeps things light after sunset. Only on the Moon does it instantly get dark at sunset due to lack of an atmosphere.
As for your cheap shot about Googling, I've been into astronomy for over 50 years. For the last 30 years I've been going to Anza Borrego desert park (about 100 miles straight south of Palm Springs) to use my telescope. I was just there for maybe the 50th time last week. It is surrounded by mountains, but as everyone out there knows; you can't really do anything much until about an hour after sunset when it actually gets "pitch dark."
"I stayed here and there was no more sun after about 3:30 over Xmas"
"No more sun" is quite different than, "Think pitch black dark by 430."
There is no place on the surface on the US, except for Alaska and forests and other places you can't see the sky, that is "pitch dark by 4:30." These are just the facts.