Heat wave, officially

On the eve of the first day of the meteorological summer, Philadelphia has recorded its first official heat wave of the season.

Rather arbitrarily, the National Weather Service defines a "heat wave" as three consecutive days of the official temperature reaching at least 90. The high at Philadelphia International Airport reached 90 on Wednesday, and 93 yesterday.

The last few days have been mightily uncomfortable, and that probably has a lot to do with the fact that we were still deploying sweaters and blankets last weekend.

Yes, this is on the early side, but pre-June heat waves are hardly unprecedented in the period of record dating to the 19th Century.

Officailly, we count at least 11 of them, starting with 1880. A second one occurred the next year.

Heat waves baked the region in April in both 1990 and 2002, and May 1996 saw three different 90-plus stretches.

The  commercial companies generally are going with temperate summer outlooks, with temperatures possibly slightly above normal around here, which would be a refreshing change from recent summers.

But the government's Climate Prediction Center's outlook has quite a warmish look.

We should point out that it had a warm look last spring also; the commercial companies were going temperate.

We don't have to remind you which worked out better.

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