Heat a life-saver?

While it did not qualify technically as a "heat wave," the warm spell that ended last night was worthy of the summer Dog Days.

But as uncomfortable as it was, it could end up being just what the doctor ordered if those long-enduring heat waves do show up later on.

Some heat-wave impact experts, such as Laurence Kalkstein, the former University of Delaware professor who developed Philadelphia's heralded heat-warning system, believe that an early hot spell can help inoculate the vulnerable population against later attacks.

That's providing that first spell doesn't lap into four or five days, in which case it would become life-threatening. This one was benignly short-lived.

Intuitively, it makes sense that a shot of heat would toughen the population, but this idea isn't embraced universally.

Dr. Donald F. Schwarz, Philadelphia's health commissioner, has experessed skepticism, noting that he had not seen any hard research to support that hypothesis.

Looking at the longer-range outlooks, the hypothesis won't be put to the test any time soon.

The government's Climate Prediction Center sees the chances favoring above-normal temperatures around here the next two weeks.

But in its morning update, the Commodity Weather Group, in Washington, said no "major" heat until at least mid-June, if then.

One housekeeping note:

We mentioned that yesterday's overnight low, 74, would have set a record for the highest minimum for the date.

Walt Drag, meteorologist at the National Weather Service, advised us that temperatures could drop rapidly in any thunderstorms, and he was correct.

Late last night, the official temperature at Philadelphia International Airport fell to 68, and that become the low for the date.