Parts of southeastern Pennsylvania in an excessive heat warning

Aug. 9—As the mercury has climb Tuesday, so has the heat alert status in part of southeastern Pennsylvania.

An excessive heat warning was issued shortly after 2:30 p.m. for Philadelphia and Delaware counties and the southern halves of Montgomery and Chester counties.

The warning reads in part: Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.

"Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles

under any circumstances."

By 3 p.m., the temperature had climbed to 95 degrees at Philadelphia International Airport and Brandywine Regional Airport and Wings Field in southern Montgomery County.

But it was hotter at Reading Regional Airport at 96 degrees while Pottstown-Limerick Airport remained cooler at 89 degrees.

Storms were beginning to fire up in the region.

Otherwise, the seemingly perpetual heat advisory in southeastern Pennsylvania is expected to run one more day and is likely to end at 8 tonight, and possibly not return for a week or more.

Berks and the northern halves of Chester and Montgomery were in the heat advisory.

The heat advisory is expected to be followed by storms and a few pleasant days the likes of which haven't been seen in the region since early July, according to AccuWeather.

With a dipping jet stream, cool air is forecast to infiltrate the region from the north and the clash of air masses will make for a good chance of storms Tuesday night and Wednesday, according to AccuWeather.

AccuWeather is going with a 90% chance of rain tonight and ditto for Wednesday.

A high in the mid-80s is expected Wednesday.

A cooler and drier air mass will be fighting through the humid air and is expected to gain control by Thursday, with a northwest wind and a high in the mid-80s, AccuWeather says.

The forecast is for a few degrees cooler Friday and Saturday with comfortable overnights across the region and countryside lows in the 50s around daybreak Saturday and Sunday.

Summer is far from over, but there are no 90-degrees days, for now, in the AccuWeather long-range forecast.

The morning lows of 76 degrees on Sunday and Monday at Reading Regional Airport were not mild enough for records. The low of 77 degrees on Tuesday morning might turn out to be a record if it holds through 1 a.m., which is when the measurement day ends during daylight saving time.

A thunderstorm at the airport would likely cool the air temporarily below 77.

The record for the mildest low on Aug. 9 is 76 degrees from 1968.

The highs during the recent hot spell haven't been close to records, having fallen on dates of major heat waves from yesteryear, including the 104- and 105-degree days from 1918 that were the hottest on record until the 106 on July 22, 2011.

Even with widespread 90s at airfields across the region on Sunday and Monday, the mercury did not get to 90 degrees at Pottstown-Limerick Airport.