It’s been well-advertised that warmer than average temperatures will finally be felt in the Philadelphia area.
The experimental statistical model statistics (EKDMOS) has a temp of about 80, with the possibility of higher (or lower):
By the way, the National Blend of Models (NBM) shows high temperatures of 76 (Friday) and 77 (Saturday).
You can see that on Sunday, 4/15, the range of temperature possibilities is quite large indicating high uncertainty for temperature highs on Sunday.
There’s a high chance of rain on Sunday, especially Sunday afternoon and evening, into Monday. Some of the rain may be very heavy.