Monday, July 02, 2012

How This Heat Wave Stacks Up So Far

We're likely on route to day five of our heat wave today...thankfully with a bit less humidity and slightly lower temperatures than yesterday.  Despite the rather nasty temperatures of the past few days, the first four days of this heat wave have been rather "middle of the pack" so far.

Over the past 20 years, there have been 50 heat waves of four days in duration or longer.  Our Heat Wave Index (the calculation of progressive heat impact over the duration of a heat wave) calculates an average rating of 44 during any four day heat wave over the past 20 years.   The first four days of this heat wave calculate in at 53 on our scale, a bit higher than average and 16th out of the 50.

More:  Heat Wave Index (how it works)

Since 1992, there have been quite a few heat waves that have packed more pop in the first four days out of the gate than this heat wave has, despite the high of 98 on Friday and 97 on Sunday.   Just a couple of years ago, we recorded back-to-back 100 degree readings, topped by 103 on July 7th, 2010.  Even that heat wave wasn't the worst of any first four day heat waves in Philadelphia.

 August 5-8, 1918, produced four rather oppressive days, including 103 and 106 (the city's gold standard for heat) on back-to-back days.  The Heat Wave Index for those four days totalled 100.

It can be...and has been...much worse.  That said, it's still rather hot out there and for those in South Jersey without power, a much more ugly situation as homes are sweltering into the upper 80's and lower 90's each afternoon in the peak of heat with this airmass in place while power outage numbers slowly come down.