Typical Weather in December. December temperatures on St. Kitts range from an average low of 76.0 degrees to an average high of 82.0 degrees. During the month of December, it rains an average of 8.0 days, with an average total rainfall of about 3.6 inches.ain is most likely to occur around 8:00 AM during the month of December, and it is least likely to occur around 2:00 AM. In St. Kitts during December, thunderstorms -- when they occur -- are most likely sometime around 2:00 AM.