Hi, Mary:
Please be aware that there is rain headed our way. A storm is right off the coast, from below San Francisco all the way up north of California. It is due to arrive tonight and will continue at a reasonable clip through tomorrow. Up here, where I'm at, we are expecting about an inch of the wet stuff; and, after that, light showers are possible through Sunday.
The thing about rain in California is that a lot of people don't know how to drive in it. I'm not so worried about you as I am about the crazies that may be around you. Even though we had a lot of rain this winter, it's been a month or better since we've seen much. When it rains here, the water brings the oil up to the surface of the road which makes it like water on ice, requiring a little extra care that not everybody takes. So, if it's raining, keep one eye on the other guy on the road because some of these guys don't slow down.
Assuming that you'll be coming from the San Francisco/East Bay area via Highway 80 and are not planning to sight-see in Sacramento, you can take Highway 505 off of Hwy 80 to avoid Sacramento and cut off a lot of traffic as well as about a half hour of driving time from your trip. Hwy 505 is a nice, quiet highway that runs into Hwy 5, north, just above the Sacramento airport. Your turn-off for the 505 will be just past Vacaville.
Also, assuming your headed north on Hwy 5 in the rain, you would probably be safe to pull off at a rest area for a few winks of sleep. Unless they are truly desperate, crooks and bad guys are just like anybody else in the rain. If it's raining pretty good and it's only going to rain that way for the day, they'll most likely wait for a dry day and leave travelers alone while it's raining.
Stay safe!