What is the climate in the central valley of California?

Our climate ranges from hot in the summer ( I have seen highs of 117 F in the summer to lows in the teens during the winter, but both of those are extremes.) During winter, we can have frost every night with heavy dense fog from late November to late February. The spring months are usually nice with 55-80 degree days. The fruit trees start to blossom as early as late January and the wild flowers can start blooming in December.

The valley has a semi arid climate so we don't really get a lot of rain, and on unusually warm winter days it can get into the 70's.