I'm from Oakland, which is located in the SF Bay Area in California.
I'd say the bay area has a pretty decent hardcore scene. People show up for shows and depending on the band, most hardcore shows will fill up the venue or club. A lot of the time you'll see the same people at most of these shows so that's a really good thing.
Some of my personal favorites at this moment include Ceremony, Sabertooth Zombie, Comadre, Final Fight, and Broadway Calls just to name a few.
Another few from the California area include...
625 is a DIY label from San Francisco. They realease thrash/hardcore albums from bands such as Punch, xbrainiax, Never Conform and more.
There are also a few cool clubs. For starters, my favorite and probably the most popular club in the Bay area has to be 924 Gilman.
A lot of bands got their start there. Some are huge and famous now, such as Green Day and AFI. But this club is really great. It is run mainly by volunteers and they have shows every Friday, Saturday and Sunday. They started off having mostly punk shows but are slowly mixing in purely hardcore and now they have a mix of both.
There is also the Submission Art Space, which is an art gallery on Mission Street in SF. They hold hardcore shows there as well.
There are also a lot of house shows here, so people plan a show and get bands to play either in their backyard but most of the times in their garage. It's pretty cool.