July 4 heatwave: A severe heatwave is gripping millions across the US, threatening July 4th celebrations with record-breaking temperatures and dangerous humidity. Outdoor events in cities like Boston and Philadelphia are being altered or canceled. Meteorologists warn of prolonged heat due to a persistent high-pressure system, urging residents to stay hydrated and avoid strenuous activity. Heat-related illnesses are a significant concern, especially for vulnerable populations.

A prolonged, dangerous heat wave will continue to intensify across most of the central to eastern U.S. into the Fourth of July weekend.

The nation is gripped in a dangerous heat dome. Threatening millions of people in the Midwest and Eastern United States.

In the U.S., hundreds of people succumb to heat-related illnesses each year

Temperatures are expected to top 100 degrees over the coming days, as high pressure traps the scorching temperatures in a heat dome.

High humidity is expected to make conditions feel even hotter