The Lehigh Valley and nearby counties will be under an extreme heat warning into the holiday weekend as temperatures are expected to exceed 100 degrees.
The National Weather Service in Mount Holly, New Jersey, initially placed the region under an extreme heat watch because extreme heat was likely, but timing was uncertain. By Tuesday, however, that had changed.
“Given the increasing confidence in significant impacts from the three to four day excessive heat and humidity with heat indices reaching into the 100-110 degree range each day, the extreme heat watch was upgraded to an extreme heat warning for all of southeastern Pennsylvania, northern Delaware, and portions of New Jersey,” meteorologists wrote Tuesday in their daily forecast discussion.
Forecasters believe high temperatures will reach 97, 101, 101 and 98 for Wednesday, Thursday, Friday and Saturday, respectively. Additionally, very warm lows in the 70s are likely during that time frame, meaning there will not be much relief from the heat.
The weather service said people should drink plenty of fluids, stay in air-conditioned rooms, stay out of the sun and check up on relatives and neighbors. Children should not be left in unattended vehicles because interiors can reach “lethal temperatures” in minutes, forecasters said.
Anyone who goes outside should wear lightweight and loose-fitting clothes. Strenuous activities should be limited to the morning or evening hours.
There could be evening thunderstorms beginning Friday and continuing through the end of the weekend. Temperatures are likely going to drop Sunday, but not by much — a high of 95 is expected.
Here is the extended forecast from the National Weather Service:
Wednesday: A slight chance of showers and thunderstorms after 2 p.m. Sunny and hot, with a high near 97. Heat index values as high as 107. Southwest wind 5 to 10 mph. Chance of precipitation is 20%.
Thursday: Sunny and hot, with a high near 101. Calm wind becoming west around 5 mph in the afternoon.
Friday: Sunny and hot, with a high near 101.
Saturday: A chance of showers and thunderstorms after 2 p.m. Mostly sunny and hot, with a high near 98. Chance of precipitation is 30%.
Sunday: A chance of showers and thunderstorms. Mostly sunny, with a high near 95. Chance of precipitation is 30%.
Monday: A chance of showers and thunderstorms. Partly sunny, with a high near 90. Chance of precipitation is 40%.