We meteorologists like to denote seasons by increments of three full months; Meteorological Summer consists of the months of June, July, and August. Astronomical Summer begins on June 21st, but it doesn't really matter anyway as our average high is already "summerlike" with a high of 78 while our average low is right around 60.
After a low of 59 at Philly International we reached a high of 77, which is pretty much an average last day of May! Sunshine gave way to clouds by noontime as we reached our convective temperature(the estimated temperature that the surface must warm to in order for clouds to develop) and there was a gusty breeze out of the northeast with a sea breeze that pushed west a good 50+ miles!
Overnight will be mostly clear with lows around 50; this will lead to a sun-filled Sunday with highs in the middle 70s as we'll have a northerly wind eventually turning more southerly by the late afternoon. This will set us up with milder air for Monday with highs in the lower 80s under plenty of sunshine.
Things begin to change on Tuesday as we'll have a cold front approach from the west, but ahead of it that southerly wind will be pumping in the heat and humidity! Highs will be in the upper 80s with showers and thunderstorms by after lunchtime! Showers and thunderstorms will linger overnight with lows around 70 and we'll start off cloudy in the morning Wednesday, but then give way to sunshine in the afternoon with highs in the middle 80s.
You can check out the rest of the 7-day forecast(any time) at www.scottderekwx.com/forecast.html.