The National Weather Service in Philadelphia reports a mostly sunny sky today with a comfortable high of near 81 degrees; gentle whispers of north winds will be brushing through at around 15 mph, gusting possibly as high as 25 mph, forecasters say. As evening blankets the city, expect the clarity to hold, with a predicted low hovering around a cool 64 degrees and north wind calming down to a subtle 5 to 10 mph.

Looking ahead, the sun will continue to grace the city on Tuesday, with temperatures taking a slight climb to reach a high near 86 degrees, the wind, seemingly indecisive, will start from the northeast at 5 mph before surrendering to the morning's calm. But don't be fooled by the serene start to the week, Wednesday night's partly cloudy skies will lead into an Independence Day festooned with a 30% chance of afternoon showers and thunderstorms the high expected to spike a sultry 92 degrees.

The latter part of the week suggests humidity will cling to the cityscape as chances of thunderstorms persist through to Sunday, intermittently reclaiming the skies from the heat, with a notable high of 93 degrees on Saturday and an ever-present possibility of rain each day leading up to it—each marked by a 30% to 40% chance of precipitation as the pattern of heat and storms settle in for a typical early July in Philadelphia.

The impending holiday may not escape unscathed by these predictions: as those planning picnics or fireworks might have to hedge their bets against the whims of this summer weather—forewarned by a clear sky that could later rumble with thunderstorms, the air heavy, expectant, and uncertain.