Heat records tied

So far the low temperature at Philadelphia International Airport stands at 77, which would tie for the highest minimum temperature recorded on a July 17.

The 24-hour low for yesterday turned out to be 80, as the airport temperature somehow tumbled 10 degrees between 9:54 p.m. and 11:51 p.m.

That tied the record for the highest minimum for a July 16.

Loyal readers might observe that we were incorrect in saying that yesterday's low set a record. Double-checking the record database, we ascertained that the actual standard for July 16 was 80, not 77.

We also stated that July 16, 2013, was all but in the clubhouse at 81. That, of course, changed just before midnight.

All that aside, yesterday's ranks as one of the warmest overnights since Philadelphia began tracking temperatures officially in 1872.

We've commented on the general increase in nighttime temperatures, and the highest minimum -- 83 -- was recorded in 2010 and again in 2011.

But steamy nights aren't an exclusively modern development. In second place, an 82 occurred during the nation's centennial year, 1876. More 82s show up in 1901, 1917, 1918, and 1925.

Sources indicate that not many folks had air-conditioning back then.

As for the rest of today and this week, the forecast is unchanged. Today, tomorrow, and Friday should be a few degrees warmer than yesterday, although you might have trouble tellling the difference.