Overview
- National Weather Service and private forecasters warn the heat dome will expand across the central and eastern United States this week and persist through the July Fourth holiday, bringing prolonged heat to the Midwest, Great Lakes, Mid‑Atlantic and Northeast.
- Daytime highs will approach or exceed 100°F in many cities and humidity will push heat index values commonly into the 100–110°F range and locally toward 115°F, while overnight lows in the 70s°F will give little relief.
- More than 100 million people are expected to face major to extreme heat risk, prompting advisories to limit outdoor exertion, use cooling centers or air conditioning, and watch for signs of heat illness.
- Europe and the UK have just come off a record June heatwave that caused transport and health service strain and multiple water‑related deaths, and forecasters say above‑average summer temperatures and additional heat spikes are likely later in July and August.
- Concurrent hazards include critical fire weather and strong winds in parts of the U.S. Southwest that worsen air quality, and scientists link the unusual breadth and intensity of these events to human‑driven warming with an active El Niño raising the odds of further extreme heat.