Philadelphia under heat advisory Sunday, few pop-up showers possible

PHILADELPHIA (CBS) -- The searing heat is back again, with highs today approaching the mid and upper 90s.

Add in humidity, and many areas across the Delaware Valley will feel like 98-102°.

The National Weather Service issued an excessive heat warning from 3 p.m. Sunday through Wednesday morning. As of now, Wednesday remains under an excessive heat watch.

While a few afternoon pop-up storms cannot be ruled out, we're likely to see them stay below severe weather criteria. Lightning will be the main threat, so if you're outside, make sure to head in at first sight.

FLASH FLOOD WARNING: The National Weather Service in Mount Holly, New Jersey, issued a flash flood warning for north central Chester County until 7 p.m.

SEVERE THUNDERSTORM WARNING: The NWS issued a severe thunderstorm warning for parts of northwestern Camden County, northwestern Burlington County and northern Ocean County, New Jersey, until 4:30 p.m. The warning also is in effect for southeastern Montgomery County, south central Bucks County and Philadelphia County until 4:30 p.m.

A severe thunderstorm warning is also in effect for parts of northern New Castle County, Delaware, southwestern Chester County and southwestern Delaware County, Pennsylvania, until 4:15 p.m.

With added humidity, it could easily feel in the low 100s Monday and 105 to 110 degrees Tuesday and Wednesday. For this reason, we've issued Next Weather Alert days for all three days.

Watches and warnings

An air quality alert is in effect for all of Central and South Jersey until 12 a.m. Monday.

A heat advisory will cover the entire Philadelphia region and Delaware Valley from 10 a.m. Sunday until 6 a.m. Tuesday. Feels-like temperatures during that time will be anywhere between 98 and 102 degrees.

Then on Tuesday morning, an excessive heat watch will go into effect for the region until Wednesday night. During that time, temperatures could feel as high as 104 to 106.

Another, but shorter, heat wave

The next heat wave shouldn't be quite as long, with another brief cooldown expected on Thursday following another cold front on Wednesday.

We're watching for a few scattered strong to severe storms Wednesday along the cold front, which will help to keep us cooler as well into the end of the week and into the weekend.

Stay with the Next Weather alert Team for the latest updates on the heat and the storms.

7-day forecast

Sunday: High of 94, feels like 102

Monday: High of 97, low of 75, NEXT Weather Alert

Tuesday: High of 99, low o 75, NEXT Weather Alert

Wednesday: High of 96, low of 80, NEXT Weather Alert

Thursday: High of 86, low of 74, showers and a few storms

Friday: High of 86, low of 69, partly cloudy

Saturday: High of 86, low of 68, partly cloudy