Heat Dome Brings High Temperatures Across Eastern U.S. Into July 4 Weekend

A heat dome is driving dangerous heat across much of the United States into the July 4 weekend, NPR reported. The National Weather Service stated on Sunday that dangerous to record-setting heat will expand across the eastern two-thirds of the country.

, extreme temperatures and humidity will be especially threatening for people with respiratory issues and the elderly, the National Weather Service said.

With the combination of high humidity, heat indices may reach 100-110 degrees. Much of the central and eastern U.S. is under a Moderate to Major HeatRisk. Parts of Iowa, Missouri, and Kansas are under extreme heat warnings.

A heat dome occurs when a very hot air mass parks itself over a region and gets trapped under a lid above the Earth's surface. Temperatures in the 90s to low 100s combined with humidity will produce heat indices well into the 100s, NWS forecaster Bryan Putnam said. Risks for extreme heat are expected to continue after July 4 and in the West.

Daytime temperatures could feel like 100 to 105 degrees and the heat could limit overnight relief, the National Weather Service said. Temperatures might stay in the 80s and 90s in the evening with humidity keeping heat indices high, Putnam said. The Missouri State Emergency Management Agency stated on Sunday that everyone should plan accordingly and limit prolonged outdoor exposure if possible.

The agency added that people should take immediate action if someone shows any sign of a heat-related illness. New York City Health Commissioner Alister Martin stated on Saturday that heat strokes are fast, deadly, and almost always preventable. The CDC notes that heat stroke can be fatal or cause permanent disability if someone does not receive emergency treatment.