Heres a monthly graph from Mar. 2013 for Siskiyou County in N. CA. Check out wunderground.com and you can get some really good WX history for your desired location. N. Cal WX has a lot of variation in both the high and low areas
Thanks for the reply's. I looked on weather underground, but you know you can only tell so much from graphs. It's good to hear from rider experience. If the weather is not good in March I'll put it back to late May. I'm heading to Chico, but I will be renting a bike and wanted to go up RT 1 and then take day trips out of Chico