Temperatures will likely exceed 100 this week in what could be a near record-breaking and dangerous few days in the Lehigh Valley.
Highs will be in the upper 90s and low 100s Wednesday through Friday, and it will feel well above that through the end of the holiday weekend, according to the National Weather Service in Mount Holly, New Jersey.
The dangerous heat and humidity will build over the Northeast and mid-Atlantic starting Wednesday, according to forecasters.
A high of 96 is expected Wednesday, followed by highs of 101 and 102 Thursday and Friday. The record highs for July 1-3 for the Lehigh Valley are 98, set in 2018; 102, set in 1966; and 105, set in 1966, respectively, according to weather service data. While records might not be broken, the temperatures will be close.
Lehigh and Northampton counties, as well as neighboring Carbon, Berks, Bucks and Monroe counties, will be under an extreme heat watch from noon Wednesday until 8 p.m. Saturday. Heat index values will be over 100 from Wednesday through Saturday, and low temperatures will be in the mid-70s to low 80s, meaning there will be little to no relief, according to forecasters.
An extreme heat watch means an extreme heat event is likely but timing is uncertain. The weather service advises to make plans to suspect major outdoor activities if a warning is issued. Those without air conditioning should locate the nearest cooling shelter or discuss staying with family or friends who do have air conditioning.
⚠️🥵 Dangerously hot and humid conditions will build Wed-Sat. High temperatures of 95-105° and heat indices of 100-110° are forecast during this period for our entire area, including area beaches and mountainous areas. Hottest Thurs-Fri. Be prepared if traveling for the holiday. pic.twitter.com/eZmuImUfU2
— NWS Mount Holly (@NWS_MountHolly) June 29, 2026
There’s little relief from the heat in sight, meteorologists said.
“Highs will remain in the low to mid 90s Sunday and [July 6] as well, with heat indices still in the mid 90s to low 100s,” meteorologists wrote Monday in their daily forecast discussion. “So we certainly could see heat related impacts continuing beyond Saturday despite a slight improvement in temperatures.”
The possibility of heat-related illnesses will significantly increase during the next few days, and people should stay in air-conditioned rooms and out of the sun, forecasters said.
There is a chance of thunderstorms Tuesday, and again Friday through Sunday.
“While details of this activity won’t become clear until later this week, it is important to point out that any holiday weekend festivities could be impacted by thunderstorms (in addition to the extreme heat),” meteorologists said.
Here is the extended forecast from the National Weather Service:
Tuesday: Sunny, with a high near 89. Light southwest wind increasing to 5 to 10 mph in the morning.
Wednesday: Sunny, with a high near 96. West wind around 5 mph.
Thursday: Sunny and hot, with a high near 101.
Friday: Sunny and hot, with a high near 102.
Saturday: A chance of showers and thunderstorms. Mostly sunny and hot, with a high near 97. Chance of precipitation is 40%.
Sunday: A chance of showers and thunderstorms. Mostly sunny, with a high near 93. Chance of precipitation is 30%.