Is this early heat a warning of a "summer of our discontent?"
Weather forecasters are quick to point out they aren't seers.
"I would say I don't see any signs at this point that this is going to be summer like, say 1988 or 1936, which are infamous hot years across vast portions of the United States," said Accu-Weather meteorologist Laura Anderson.
"The 30-day forecast for mid-June to mid-July is for above normal temperatures in this area," said National Weather Service meteorologist Jim Poirier. "Whether that will continue on for the rest of the summer is really not known."
An excessive heat warning has not yet been issued in Philadelphia, said Health Commissioner Estelle B. Richman. But still she called for heat-related caution.
The prediction of a heat and humidity index of 105 degrees for two consecutive days, for three or more hours daily, is required before an excessive heat warning is issued by the weather service, Richman said.
Yesterday's local heat index, the equivalent of winter's wind chill, was 96.
In a meteorological quirk, it was 109 in Plattsburgh, N.Y., while the actual high temperature hit 100 degrees in Burlington, Vt.
It was still hot enough in Philadelphia for health officials to urge caution for the elderly, ill, pregnant women, small children and those engaged in strenuous physical activity.
These hot weather rules were suggested: Wear a hat, use an air conditioner or fan, open windows to release trapped hot air, never leave older people, children (or pets) alone in cars, drink plenty of nonalcoholic liquids, and shower or bathe in water near skin temperature.