There's a pretty decent chance that the beginning of next week will be the warmest we've seen since our foray of May in March three weeks ago. In fact, it's possible that it could be the warmest of the season for Philadelphia (80 degrees is our gold standard in heat this year so far) depending on the evolution of the pattern. While there are lots of variables at play on the map for how warm we can get ultimately get, the potential is there some summer-like weather for the beginning next week.
The question will then turn to a cool front that the models try to push into the region early next week. The GFS stalls the front overhead on Monday, with showers, storms, and clouds along the front and part of our region's weather through Wednesday, when a low pressure center pushes through the Mid Atlantic and pushes everything through. The Euro is a bit slower with the approach of the front and tries to keep the front to our north through Tuesday...and more importantly, keeps this bigger low pressure center to our west through much of next week.
The differing details means that if the Euro is right, we could see 80+ on Monday and perhaps Tuesday in Philadelphia, while the GFS only suggests 70's on Monday and cooler air (60's?) on Tuesday of next week as the front hangs around the region. Also, the GFS brings a bit more rain to the region in the Tuesday/Wednesday timeframe while the Euro pushes the low slowly through on a Thursday/Friday timeframe, with warm temperatures (not as warm) through the balance of next week. The strength of the Carolina/Bermuda high will ultimately determine how long the warmth lasts and how warm it ultimately is.
The details will be fine tuned down the line, but take this is a heads up that summer may try to sneak in here for a couple of days early or even the middle of next week.