Heat wave expected across much of the United States through July 4 weekend
The National Weather Service warned that dangerous heat and high humidity will affect most of the country, with heat indices reaching 100-110 °F and health officials urging precautions.
A broad heat wave is set to cover most of the United States through the July 4 weekend, according to the National Weather Service (NWS). The agency said a “dangerous to record-setting heat” will spread across the eastern two-thirds of the country, with heat indices in some areas reaching 100-110 °F.
The combination of high temperatures and humidity is expected to pose health risks, especially for the elderly and people with respiratory conditions. The NWS noted that much of the central and eastern U.S. is under a Moderate to Major Heat Risk, which can affect those without adequate hydration or cooling.
Extreme heat warnings have been issued for parts of Iowa, Missouri and Kansas, while Ohio, North Carolina and Washington, D.C. face particularly threatening conditions. A heat dome—a hot air mass trapped under a high-pressure “lid”—is driving the pattern.
"You get temperatures in the 90s to low 100s, that's obviously pretty hot. But you combine that with the humidity, those heat indices will go well into the 100s and that's the temperature that it's going to feel like," NWS forecaster Bryan Putnam told NPR.
The NWS cautioned that high heat indices are likely to persist after July 4, especially in the West, where daytime feels could reach 100-105 °F with limited overnight relief. Putnam advised people gathering for fireworks to remain vigilant, noting that temperatures may stay in the 80s-90s after sunset and humidity will keep heat indices high.
State and local officials urged residents to limit outdoor exposure, stay hydrated, and use air conditioning. The Missouri State Emergency Management Agency recommended planning ahead and taking immediate action if heat-related illness symptoms appear. New York City Health Commissioner Alister Martin warned that heat stroke is “fast, deadly, and almost always preventable,” and advised checking on neighbors and using cooling measures.
The Centers for Disease Control and Prevention highlighted heat exhaustion, heat rash and heat stroke as common heat-related illnesses, with symptoms such as nausea, headache, confusion and dizziness.
