Philadelphia's climate is prone to extremes on occasion -- be it ice, snow, cold, heat, rain, and humidity. We seem to have run the gamut of those extremes over the past five years in stretches of time. In terms of extreme days, I thought on our 8th 90 degree day in a row to share the "worst of the worst" in terms of temperatures...both hot and cold, with the latter to help us think cool thoughts on another summer day.
The last two complete summers (2010 and 2011) have brought us three of the nine hottest days on record...all occurring in July. July 7th, 2010 hit 103 in Philadelphia, with July 22nd last year hitting 103 as well. The average temperature last July 22nd was the 2nd hottest on record in Philadelphia and the hottest on record for the Airport site, which has been around since 1940. The July 23rd low temperature (83) was the highest on record in Philadelphia and the daily temperature ties for 5th on the all-time chart.
The coldest days on record (there are ten as one from the 1910's ties with 1895 and 1982 for an average temperature of 3...it's just not listed) are a chilling reminder of what has happened in our past. While it's been eighteen years since our last subzero low in Philadelphia, occurring on January 19th, 1994, the average temperature for that icy cold January day is the 4th coldest on record. The 1970's, 1980's, and 1990's have a fairly large representation in our temperature list as four of the ten coldest days were in the past 35 years...of course, the coldest days on record occurred decades ago -- 1934 and 1899 featured the coldest days on record in Philadelphia (an average daily temperature below zero, the only two instances on record in the city), with the 1899 cold outbreak bringing a follow up performer to February 10th with its near encore on February 11th ("high" of 10, low of six below).
Given our trends in urbanization and increased "heating" in metropolitan Philadelphia, it might be tough to reach the cold standard low of 1934 at any point in the future but on a hot day these chilling reminders of what has happened in the past should get temporary comfort as you sweat it up outside.