Average Temperatures for Philadelphia. Philadelphia's coldest month is January when the average temperature overnight is 25.5Â°F. In July, the warmest month, the average day time temperature rises to 85.5Â°F.The driest month in Philadelphia is February with 2.74 inches of precipitation, and with 4.39 inches July is the wettest month.n July, the warmest month, the average day time temperature rises to 85.5Â°F. The driest month in Philadelphia is February with 2.74 inches of precipitation, and with 4.39 inches July is the wettest month.
1 A data set has three quartiles: the lower quartile, the median of the data set, and the upper quartile. 2  Median: The median divides a data set into two equal parts. 3  Lower quartile: Median of the lower half of the data. 4  Upper quartile: Median of the upper half of the data.
Quartiles are a useful measure of spread because they are much less affected by outliers or a skewed data set than the equivalent measures of mean and standard deviation. For this reason, quartiles are often reported along with the median as the best choice of measure of spread and central tendency, respectively, when dealing with skewed and/or data with outliers. A common way of expressing quartiles is as an interquartile range.