While traveling through the area I found a Wholefoods which does have SOME kosher products. You will also be close enough to San Fran and its suburbs, of particular relevance being Palo Alto, which all have a very large selection of kosher establishments...
Molly Stone - a supermarket in Palo Alto with a VERY LARGE selection of kosher products...
Do it, it is a marvelous area!
Monterey is 80 miles from Palo Alto. Part of the road that you would take to get to Molly Stone's is the treacherous Highway 17. That's 20 miles of two lanes with locals passing like demons around blind curves. If you drive towards Palo Alto on Sunday morning
and then come back in the afternoon, you will be avoiding the bulk of the traffic. A lot of people in the Silicon Valley drive to Santa Cruz during good beach weather on Friday and
go back to San Jose, etc., on Sunday afternoon/Sunday evening.
The Monterey Bay is a beautiful area but the Kosher options are the open a can or cook it yourself variety. There are no kosher restaurants in Monterey, Santa Cruz, Capitola, etc. It's like being in Montana.
Chabad of Monterey, in recognition of the difficulty of finding kosher options, offers lunch, dinner and Shabbos food for the ordering: