The ZEMA graph shows daily temperatures for December 2015, according to AccuWeather, for San Diego (red line), Chicago (green line), San Antonio (black line), and New York City (blue line). The temperatures are in degrees Celsius.
During December 2015, the temperature seasonally dropped in Chicago at timers reaching -10 C. In New York, while fluctuating, it remained above the freezing point. San Diego hardly noticed any winter signs with temperature remaining steady around 10C. San Antonio experienced a significant drop (by almost 20 degrees) to almost zero following the Boxing Day and after that staying low.
Data Sources: AccuWeather