California is a special place. Seeing those videos gives you an idea of why a lot of Californians choose not to go to far away destinations.
It's cold though, many spots like Lobos can easily hover in the mid to upper 40's.
That's also the reason for so much profuse marine life.
California's a big state. The far southern end is completelydifferent from the far northern end.
However there are a few crossover species that are seen in both, but many that are not.
The south has lobsters and those orange fish called Garibaldis.
The northern end tends to look a lot like the PNW with Puget Sound king crabs, giant pacific octopus, big wolf eels, and big lingcod.
Lobos is somewhere in between.
The Monterey, Carmel, Big Sur area can get some incredible vis because of the cold water that comes up from the trench right offshore from Carmel.
Here in California the water is actually the coldest in spring when the winds come up from the inland valleys heating up and drawing in cold ocean air. This action also causes the water to upwell, that's when the deeper Alaskan current gets sucked up by the wave action. The water can get down into the low 40 sometimes during these spring winds. Along with the ice cold water comes lots of nutrients, and when the nutrients get exposed to sunlight they bloom.
Summer it starts to calm down but the long daylight can cause more of the aformentioned and dreaded algae blooms and the vis can go to crap in a few hours literally and last for days /weeks.
Fall the winds calm down and the days start getting shorter and the blooms are not as frequent. Winter time right before a storm I have seen vis soar to 80 or 90 feet with glass flat conditions. Then the next day all hell breaks loose and 20 footers are rolling in.
Like Akimbo said, you really have to be a dive bum to be able to catch those windows. I actually happen to be one of those bums since I am self employed (ahem,.. I mean, I'm booked solid that day, I'm sorry).
The Northern end of the state is where I am from and up around Mendocino (where Akimbo lives) I have had some of the very best dives of my life. One day at Arena Rock (do a search) vis was in excess of 80' feet. On another trip just south of Mendocino Vis was in excess of 90' feet (maybe even 100', hard to tell) but it was also ice cold 45-46 degrees. This was in August.
The North Coast (Sonoma & Mendocino County) is like 60 miles of Point Lobos on steroids.
The north though is hard to get to, there are no charter boats, you really have to know someone and have the flexibility and the support system to stay for a couple weeks and be able to hit the spots when they are prime. It's almost like surfing in a way, except the opposite conditions.