The pumpkins love it here
I shouldn't be surprised - I pass a pumpkin farm on the way to work. But I grew up in the Bay Area of California, where the tradition is to go to the pumpkin patches of Half Moon Bay, so some part of me still thinks you must need fog and chill to grow them.
Mine here are volunteers. I just bought this house this year, and there was a hole in the yard, where the previous owner had uprooted a tree to take with him when he left. I had a rotting pumpkin sitting around - doesn't everybody?-so I tossed it in the hole and enthusiastically chunked it up with a spade.
Fast forward to a few months later when I planted bell peppers in the spot, first amending the soil with a bit of organic 4-4-4 fertilizer. You can guess what happened next. The peppers are still there by the way, and attempting to produce, but of course are totally overwhelmed by the pumpkins, 4-5 of them. I expect to get about three medium-sized and five small pumpkins out of my little patch.
I did have a bit of a problem with squash bugs, which turned up end of June/early July. I hand-picked the adults (often found beneath the fruit, mating) and scraped/squished the eggs, or removed the parts of the leaves with the eggs (to be drowned in soapy water). What is working for me is to make a pass and just look, and then to get the garden hose to spray the leave from beneath. This kind of blows back the leaves so I can see more eggs underneath, and will send the adults running around where I can see them, too. This is an early-morning or late-afternoon activity, such as not to fry the vegetation, as they are in full sun most of the day.
It seems gardeners in a lot of places devote a lot of effort to prevent getting the leaves of their plants wet. I can see how that might be a problem in a humid climate, but here the relative humidity is about 15% in the summer, and I don't worry about it.
In checking Gardenweb to find out what to do about the things (I'm gardening organically, so my options are limited) I read a lot of horror stories about squash vine borer. But a little further research revealed that their range is east of the Rocky Mountains, and they are not an issue here.
These pumpkins are obviously the type grown for Halloween Jack-o-lanterns. Next year, I plan to plant different varieties, one more for looks, and one suited to cooking. Since I'll be growing them on purpose, I expect an epic fail. :)