Erica's Answer:
Record lows of 43 degrees and 41 degrees were reached on May 20th and 21st, respectively, in Philadelphia. In the meantime, we have brand-new record highs on the books from just last month, during that first brutal June heat wave. As the Philadelphia area gets bigger and bigger, it becomes increasingly difficult for us to achieve record lows. That is because of a factor called the "Urban Heat Island" effect. The increase in the number of people, buildings, cars, and the like inhibits our atmosphere from cooling off at night.- Erica
