‘Dangerously hot’ and humid conditions to continue this week in Lehigh Valley. What’s fueling the heat wave?

Excessive heat will continue for several days in the Lehigh Valley, with the possibility of storms later this week.

The National Weather Service is predicting highs in the 90s through Wednesday, while the area remains under a heat advisory through Tuesday evening. Heat index values will be 104 Tuesday and 102 Wednesday, according to the weather service.

Mike Gorse, meteorologist for the local weather service office in Mount Holly, New Jersey, said this heat wave is similar to the ones the region has seen in recent weeks. The humidity, he said, is lasting longer.

There’s a big strong area of high pressure, Gorse said, adding that it acts as a “heat pump.”

“It just keeps the heat basically locked into the mid-Atlantic region,” he said.

Monday was the fourth day in a row with temperatures in the 90s, and that is expected to continue through Wednesday, which has an expected high of 93. Forecasters said “dangerously hot” and humid conditions are expected Tuesday, and could continue Wednesday. That could change if clouds move in earlier.

The weather service said there is a 70% chance of storms Wednesday into Thursday while the remnants of Hurricane Beryl track toward the region. Storms during that period could cause heavy rain and flash flooding, according to officials. The hurricane made landfall Monday morning in Texas.

There is a 60% chance of storms Friday.

Temperatures should cool down to the 80s Thursday, Friday and Saturday, but will return to the 90s by Sunday.

Here is the extended forecast from the National Weather Service:

Tuesday: A chance of showers and thunderstorms, mainly after 2 p.m. Partly sunny, with a high near 96. Heat index values as high as 104. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tuesday Night: A chance of showers and thunderstorms, mainly before 2 a.m. Mostly cloudy, with a low around 76. Southwest wind around 5 mph becoming calm. Chance of precipitation is 30%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Wednesday: Showers and thunderstorms likely, mainly after 2 p.m. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 93. Light south wind increasing to 5 to 10 mph in the afternoon. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Wednesday Night: Showers and thunderstorms likely, mainly before 2 a.m. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 75. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Thursday: Showers and thunderstorms likely, mainly after 2 p.m. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 89. Chance of precipitation is 70%.

Thursday Night: Showers and thunderstorms likely, mainly before 2 a.m. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 73. Chance of precipitation is 60%.

Friday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2 p.m. Partly sunny, with a high near 87. Chance of precipitation is 60%.

Friday Night: Showers likely and possibly a thunderstorm before 8 p.m., then a chance of showers and thunderstorms after 8 p.m. Mostly cloudy, with a low around 71. Chance of precipitation is 60%.

Saturday: A chance of showers and thunderstorms. Partly sunny, with a high near 88. Chance of precipitation is 50%.

Saturday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 70. Chance of precipitation is 30%.

Sunday: Mostly sunny, with a high near 92.