Erica's Answer:
It's definitely true that moving the location of weather observations will distort their accuracy over the course of decades, but we have no way of knowing whether the high and low temperatures would have been skewed higher, lower, or not at all on any given day. Keep in mind that there are lots of changes that happen other than the movement of the observation's location. For instance, the city of Philadelphia has gotten a lot larger since 1940, so the urban heat island effect is larger. The urban heat island effect is the warming that occurs in cities due to the larger number of people, automobiles, and black pavement—all of which make the city environment warmer. However, the airport is more prominently located near the water than Center City Philadelphia. The Delaware Bay is usually cooler than the air in the summer and warmer than the air in the winter, so the Bay's influence may have an effect on those weather observations. As a side note, the highest temperature and the lowest temperature ever recorded in Philadelphia are both from the old observation site at 9th & Chestnut in Center City.- Erica
