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Extreme Heat Watch Issued for Region Through July 4

June 28, 2026 · wweather1 editorial · 2 min read

The National Weather Service (NWS) Mount Holly NJ has issued an Extreme Heat Watch for multiple counties in Delaware, New Jersey, and Pennsylvania, effective June 28 until July 4. Dangerously hot conditions are anticipated, with heat index values possibly reaching 110 degrees.

An Extreme Heat Watch has been issued by the National Weather Service (NWS) Mount Holly NJ. The watch is in effect from June 28 at 3:57 AM EDT until July 4 at 8:00 PM EDT.

Dangerously hot conditions are anticipated, with heat index values possibly reaching up to 110 degrees during daytime hours. The hottest conditions are forecast to occur Thursday through Friday. Very warm low temperatures, ranging from the mid-70s to low-80s at night, are not expected to offer relief from the heat. This combination with multiple days of near record-breaking temperatures is expected to exacerbate the impacts of heat and humidity.

The Extreme Heat Watch affects several counties. In Delaware, New Castle County is included. In New Jersey, the watch covers Mercer, Camden, Gloucester, and Northwestern Burlington Counties. In Pennsylvania, affected areas are Delaware, Eastern Chester, Eastern Montgomery, Lower Bucks, and Philadelphia Counties.

These extreme heat and high humidity conditions significantly increase the risk of heat-related illnesses.

Why it is dangerous and what to do

⚠️ Safety
• Drink plenty of fluids.
• Stay in an air-conditioned room and stay out of the sun.
• Check up on relatives and neighbors.
• Do not leave young children and pets in unattended vehicles.
📊 The numbers, from wweather1 data
Philadelphia: now +27°, Overcast.
That is 1° above the June climate norm.
The record for this date is +35° (2010).
Three-day forecast: 28 June: +28°/+21° · 29 June: +32°/+18° · 30 June: +34°/+19°
The figures are computed automatically from the Open-Meteo/ERA5 archive — no eyeball estimates.

🌍 Weather in nearby cities

📰 Data source: NWS. Forecast and analysis — wweather1, based on Open-Meteo / met.no data.

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