After a few more days of below average temperatures, the upper level energy that's brought us back-to-back 60's on Monday and today will pull away and allow for a warming trend into the weekend. Starting tomorrow, temperatures will increase each day into the weekend by anywhere from three to five degrees -- it's not a huge change each day but given how cool the past couple of days have been these increases won't be enough to get us out of the below normal hole we were in until week's end. By Friday, we should be near or above average (80 degrees) for high temperatures.
From there, could 90 be in the cards for some of us this weekend? Perhaps on Sunday, especially south of Philadelphia. The Euro (below) shows its raw temperature output for the model for Sunday afternoon at 5 PM, with orange shading the areas where temperatures could exceed 90 degrees. It would include a good chunk of Delaware and portions of Southwest New Jersey, with mid and upper 80's common for much of the rest of the Delaware Valley.
Similar warmth would be possible for Monday as well, perhaps even a notch or two warmer than Sunday's projections. Monday may be the region's best overall chance at 90 degree temperatures as thunderstorms move on in Tuesday afternoon and evening (although 90 could certainly be reached Tuesday afternoon in some spots).
The bad news with next week's front is that early modeling shows the potential of a stall out of the front near or close to the region...which would result in thunderstorm chances in the afternoon for late next week. Granted, that's still over a week out so hopefully we'll see a speedier frontal passage but given it's summer and fronts are a bit less potent at this time of the year it would not surprise us to see a late week stall out.