Tuesday was a hot day, but it wasn't that humid; after a morning low of 69 at Philadelphia International Airport we had sunshine and fair weather cumulus popping up in the afternoon once we reached the convective temperature(the estimated temperature that the surface must warm to for clouds to develop). The high reached 90 degrees shortly after 3pm which is the hottest it's been all August(it took 26 days!). This was thanks to a southerly flow as high pressure is still on top of the region, but the closer to the shore you were there was a southeasterly wind which caused a sea breeze off of the 75-degree ocean.
Overnight will be mostly clear, but don't be shocked to see some fog forming as well since humidity levels are rising; lows will range from the middle 60s in the suburbs to around 70 in Center City; Wednesday will be in the lower 90s with hazy, hot, and humid conditions. There will also be increasing clouds thanks to an approaching cold front, however the front will be moisture starved so I feel that north and western areas(around elevations) have the best chance of seeing showers and thunderstorms in the afternoon.
After leftover clouds/showers overnight with a muggy low in the lower 70s we'll kick out the clouds by the morning and have a sun-filled afternoon. There will be a northerly wind with highs in the middle 80s as that frontal boundary will be south of the region; come Friday that front will be pushing back northward as a warm front just in time for the Labor Day weekend. There will be an onshore flow with highs in the lower 80s, but there will be clouds in the late afternoon with an isolated shower or thunderstorm as the warm front passes northward overnight as lows will be around 70.
For the entire Labor Day weekend it will feel more like the Fourth of July with a hazy, hot, and humid feel; highs will be in the upper 80s to around 90 with a lingering threat of showers and thunderstorms each afternoon as we'll have that sticky air mass on top of us and there won't be much relief until the frontal boundary pushes through overnight Monday. I don't feel there will be any washouts, but parties, barbecues, or even just a relaxing day at the beach or pool may be interrupted with a brief 30-45 minute shower.
So remember to keep an eye to the sky this upcoming weekend, but also keep checking my 7-day forecast(as well as obtain radar and satellite maps) any time at www.scottderekwx.com/forecast.html.