As noted in today's Inquirer, Philadelphia set a record for the warmest June with an official average temperature of 78.2.
While it was hot all over the place, the official readings, taken at International Airport, made Philadelphia a regional hotspot, and it's possible that all that nearby development is having an impact on the readings.
It also was the warmest June on record in Atlantic City, where it hit 90 or better 14 times, the most ever. In the remarkably hot summer of 1991, it reached 90 in June 11 times, but that's now a rather distant second.
But the June temperature at AC was a less toasty 75.8, and it would make sense that the Shore would be a few degrees cooler than the mainland.