Philly heat wave is official, and the humidity sets in
The higher moisture content in the air and the heat also might generate isolated showers and thunderstorms.
The first two days of the first heat wave of the year were indeed hot, but the humidity was kept in check. That all changed Friday, and the sticky summer feeling in the air is expected to hang around Saturday, too.
The National Weather Service reported that the mercury surpassed 90 degrees at Philadelphia International Airport on Friday afternoon, officially marking the first heat wave — three consecutive days of 90-plus temperatures — of the year.
As temperatures climbed to 93 degrees in Philadelphia on Friday, dew points also rose into the low 60s, bringing a mugginess to the once-dry heat. It was slightly cooler at the New Jersey Shore, as temps hovered in the high 80s, with dew points also in the 60s.
The steamy weather is slated to stay through Saturday, causing the heat index to hover in the mid-90s Saturday before a “strong cold front” hits Saturday evening, according to the weather service.
The heat, increasing low-level moisture, and other atmospheric factors also were providing the ingredients for isolated showers and thunderstorms expected Friday evening, the weather service said. The weather service issued several thunderstorm and flash flood warnings for the Pottstown and Allentown areas Friday evening.
For the second day in a row, officials issued a code orange air quality alert for the Philadelphia region Friday, from the city’s western and northern suburbs to the Shore.
The alert mean air pollution concentrations could be unhealthy for sensitive groups, including children, the elderly, and people suffering from asthma, heart disease or other lung diseases. Those folks are urged to avoid strenuous activity or exercise outdoors. The warning is likely to extend into the weekend.
Saturday is expected to be the last day in the 90s — 94 degrees is the forecast high for Philadelphia — before things cool off with the mercury topping out in the mid-80s Sunday and Monday.
The cold front also will bring an increased chance of thunderstorms Saturday and Sunday. The weather service says some thunderstorms Saturday afternoon and evening may produce strong or damaging winds.
Expect the heat and humidity to return Tuesday.