Maybe this just applies to approximately the latitude of Philadelphia, but the almanac I use gives the length of the day (meaning daylight) for each Sunday. Today the length was 9 hours, 27 minutes. Next Sunday it will be 9 hours, 22 minutes. On December 20, the day before the Winter Solstice, the length will be 9 hours, 20 minutes. On December 27, the length will have crept back up to 9 hours, 22 minutes.
(I forgot today is St. Nicholas' Day, and next Sunday is St. Lucy's Day.)