suddenly we have TONS of these - ID please

I live in Northern California, almost the oregon border, along the coast.
These guys showed up same time last year, as we got closer to fall and the end of summer.

This year I tore up a huge deck on the side of the house, saw TONS of different kinds of spiders, including a few black widows. Once the debris was gone, these guys started showing up everywhere. Last year there was probably a dozen total that you could see, almost always connected to the roof of our house and then to a nearby tree or shrub.

Now they are everywhere. It seems like every time I walk outside I end up walking through a web of theirs. You can see the little lines of web in the air coming off the side of the house and after spending countless hours scouring the web for specific info on these things, im coming up empty handed.

This one is a little over an inch and a half, but they are all different in size, but look identical for their markings. some have big thick bodies, others are skinny like this one or just babys.

so, what the heck is it? should I be worried? We have a infant at home and I found one crawling across her bedroom floor the other day which of course freaked us out.
Thanks.

That's a harmless Common Orb Weaver, Araneus diadematus, also known as a "Cross Spider", because of the pattern on its abdomen. The big fat ones are gravid females, while the others are either males or immature females. They are nothing to worry about, and they can in fact be quite beneficial in killing insects like mosquitoes or grasshoppers.

pitbulllady

There is nothing to worry about with this species, absolutely harmless. HOWEVER, they do have a nasty yet nifty defense if you bother them... a guy found one and freaked out at work so i caught it and i was letting it walk around on my hands and stuff, set it down and went to pick it up again and it turned around and sprayed this HUGE stream of poop at me! Talk about nasty.
-Nate