San Diego County is going to be unusually cold for a second straight week as a pair of low pressure systems bring showers and possibly light snow to the region, says the National Weather Service. The first system will arrive on Monday and will prevent the daytime high from rising above 62 in San Diego, which has an average high of 65 this time of year. The temperature will be 57 on Tuesday and 60 on Wednesday. Inland valleys and foothills will mostly be in the 50s, with some areas 5 to 10 degrees below average.