At 3 p.m. it was 93, and it felt like . . . 93.
"It's not as oppressive as we expected it to be," said Gary Szatkowski, the head of the National Weather Service office in Mount Holly, which had issued a heat warning.
That warning remains in effect Thursday, since it should be 3 or 4 degrees toastier and more humid. And as has been the case often in recent summers, the night-time warmth has been at least as impressive than the day-time heat.
In fact, there's a chance Philadelphia will break a record for highest minimum temperature for a June 24th. The forecast low was 76, a degree higher than the record.
No deaths have been reported in this heat wave, which began Sunday, but health officials say that the lack of night-time cooling is a serious concern. The temperature hasn't dipped below 70 since Saturday.
"We really worry about the nights as much as the days because of the cumulative impact," said Szatkowski. Overnight heat is a menace in the rowhouse neighborhoods where the vulnerable elderly population tends to live.
Without cooling when the sun goes down, those homes heat up in a hurry after daybreak. Szatkowski added that right now, the sun is beating on rooftops with maximum ferocity because it's so close to the solstice.
Factors inhibiting cooling after sunset include urban buildings and paved surfaces, which decrease cooling after sunset, and perhaps an increase in water vapor in the air as a result of worldwide warming. Vapor retards heat from escaping into space.
Whatever the reasons, an Inquirer analysis shows that in the last 30 years, the nights have warmed twice as rapidly the days compared with the previous 30 years. The highs increased from 84.1 to 85.2, and low from 64.8 to 67.3.
It didn't get below 73 Wednesday morning, but the region caught a major break in the afternoon with a strong west wind that knocked out some of the water vapor, said Szatkowski.
