San Diego Weather In December
San Diego Weather In December is heavenly in comparison to the most of the rest of the US. The average high temperature is around 66F, and the average low is barely brisk at 48F. December is the wettest month of the year in San Diego, however, at around 9 inches on average for December. You may want to bring an umbrella or poncho, although the chances are still in your favor for dry, warm December San Diego Weather.