A "typical" June and August are going to set the tempo for a very warm, but not record breaking summer in terms of temperatures in Philadelphia. Given current trends, this summer will shape up as one of the ten warmest since 1872 but it will not be a top five warmer in terms of warmth given temperature forecasts between now and month's end.
Meteorological summer ends on Friday with the end of August.
We're currently tied for 5th warmest of all time at 78.0 with last summer but with the coming week's weather not terribly hot and in fact relatively nice on Wednesday and Thursday it looks like we will be able to drop a notch, perhaps two notches, on the warmest summer list between now and Friday. This summer likely ends up tied with either 1991 or 2005 for 6th or 7th warmest based on projected highs and lows over the course of the next five days. August 2012 likely ends up flirting with the top ten but may come up just short of the 10th warmest August on record.
It's still plenty warm and it's the third consecutive top ten warmest summer on record, with the mid 90's stretch of summers setting three consecutive gold standard years between 1993 and 1995 standing ahead of us as well. The thing that stands out in the "warmest summers" parade is that all ten of the warmest summers on record, including tenth place 1999 (not shown above) have occurred since 1991. Prior to 1991, the warmest summer on record occurred three times (1900, 1973, 1988) at 77.1 degrees.