Sunday was your textbook average late August day; after a morning low of 64 at Philadelphia International Airport there was sunshine and fair weather cumulus in the afternoon. This propelled the high to 83 degrees shortly before 4pm; this was thanks to high pressure and an easterly(onshore) wind between 10-15mph.
The clouds dissipated once the sun set so overnight it will be clear and seasonably cool with lows in the lower 60s(50s north and west); Monday will feature sunshine, fair weather clouds in the afternoon, and the wind will be variable from out of the north in the morning to from out of the southeast by the afternoon. Highs will be in the lower 80s once again. On Tuesday there will be more of a southerly to southwesterly wind as highs approach the middle 80s as a warm front progresses to the north in the afternoon. Come Wednesday a cold front will be approaching from the west so highs will be near 90(it will be hazy, hot, and humid) with showers and thunderstorms by the late afternoon and overnight(lows will be in the soupy lower 70s).
Morning showers and clouds will give way to some sunshine in the afternoon with highs in the middle 80s, but Friday we'll have a northerly flow so highs will be in the lower 80s, but it's short lived as another surge of warm air progresses northward for the Labor Day weekend. Highs on both Saturday and Sunday will be in the upper 80s with overnight lows around 70; there will be scattered showers and thunderstorms in the afternoon as a frontal boundary is draped across the region.
Remember that you can check out the 7-day forecast(as well as obtain radar and satellite maps) any time at www.scottderekwx.com/forecast.html.