Even though July is barely a week old, a second heat may have already begun.
A high of 92 is expected today, followed by temperatures reaching the low 90s Tuesday and Wednesday, with overnight lows in the low to mid 70s, according to the National Weather Service.
A possibility of thunderstorms runs from Tuesday afternoon through Wednesday night.
Relief should come Thursday, with a few straight days topping in the mid 80s, with overnight lows in the upper 60s.
Three straight days of 90 degrees or more is the minimum required for a heat wave.
The high for the year, 96 degrees, was reached on July 2, in the middle of the year's first heat wave.
Last year had two heat waves before July, one from May 29 to June 1, another from June 24 to 26, with the first of July's two from the 4th to 7th.
July got off to a much more scorching start just two years ago, with 17 of the first 18 days surpassing 90 degrees, and two days hitting the 100 mark.
Two years ago today, the temperature hit 101.
July 2011 had a super-steamy second-half stretch, hitting 98, 103, 101 and 98 again from the 21st to the 24th.
See the latest forecast.
Contact staff writer Peter Mucha at 215-854-4342 or email@example.com.